--- a/src/driver.cpp	Thu Jun 05 16:55:00 2008 +0000
+++ b/src/driver.cpp	Thu Jun 05 20:54:52 2008 +0000
@@ -87,7 +87,7 @@
 				delete newd;
 			}
 		}
-		error("Couldn't find any suitable %s driver", GetDriverTypeName(type));
+		usererror("Couldn't find any suitable %s driver", GetDriverTypeName(type));
 	} else {
 		char *parm;
 		char buffer[256];
@@ -125,7 +125,7 @@
 			const char *err = newd->Start(parms);
 			if (err != NULL) {
 				delete newd;
-				error("Unable to load driver '%s'. The error was: %s", d->name, err);
+				usererror("Unable to load driver '%s'. The error was: %s", d->name, err);
 			}
 
 			DEBUG(driver, 1, "Successfully loaded %s driver '%s'", GetDriverTypeName(type), d->name);
@@ -133,7 +133,7 @@
 			*GetActiveDriver(type) = newd;
 			return newd;
 		}
-		error("No such %s driver: %s\n", GetDriverTypeName(type), buffer);
+		usererror("No such %s driver: %s\n", GetDriverTypeName(type), buffer);
 	}
 }
 

--- a/src/fileio.cpp	Thu Jun 05 16:55:00 2008 +0000
+++ b/src/fileio.cpp	Thu Jun 05 20:54:52 2008 +0000
@@ -186,7 +186,7 @@
 	FioFreeHandle();
 #endif /* LIMITED_FDS */
 	f = FioFOpenFile(filename);
-	if (f == NULL) error("Cannot open file '%s'", filename);
+	if (f == NULL) usererror("Cannot open file '%s'", filename);
 	uint32 pos = ftell(f);
 
 	FioCloseFile(slot); // if file was opened before, close it

--- a/src/gfxinit.cpp	Thu Jun 05 16:55:00 2008 +0000
+++ b/src/gfxinit.cpp	Thu Jun 05 20:54:52 2008 +0000
@@ -55,7 +55,7 @@
 		load_index++;
 		sprite_id++;
 		if (load_index >= MAX_SPRITES) {
-			error("Too many sprites. Recompile with higher MAX_SPRITES value or remove some custom GRF files.");
+			usererror("Too many sprites. Recompile with higher MAX_SPRITES value or remove some custom GRF files.");
 		}
 	}
 	DEBUG(sprite, 2, "Currently %i sprites are loaded", load_index);

--- a/src/network/network_server.cpp	Thu Jun 05 16:55:00 2008 +0000
+++ b/src/network/network_server.cpp	Thu Jun 05 20:54:52 2008 +0000
@@ -323,12 +323,12 @@
 		Packet *p;
 
 		// Make a dump of the current game
-		if (SaveOrLoad(filename, SL_SAVE, AUTOSAVE_DIR) != SL_OK) error("network savedump failed");
+		if (SaveOrLoad(filename, SL_SAVE, AUTOSAVE_DIR) != SL_OK) usererror("network savedump failed");
 
 		file_pointer = FioFOpenFile(filename, "rb", AUTOSAVE_DIR);
 		fseek(file_pointer, 0, SEEK_END);
 
-		if (ftell(file_pointer) == 0) error("network savedump failed - zero sized savegame?");
+		if (ftell(file_pointer) == 0) usererror("network savedump failed - zero sized savegame?");
 
 		// Now send the _frame_counter and how many packets are coming
 		p = NetworkSend_Init(PACKET_SERVER_MAP);
@@ -355,7 +355,7 @@
 			p->Send_uint8(MAP_PACKET_NORMAL);
 			res = (int)fread(p->buffer + p->size, 1, SEND_MTU - p->size, file_pointer);
 
-			if (ferror(file_pointer)) error("Error reading temporary network savegame!");
+			if (ferror(file_pointer)) usererror("Error reading temporary network savegame!");
 
 			p->size += res;
 			cs->Send_Packet(p);

--- a/src/newgrf.cpp	Thu Jun 05 16:55:00 2008 +0000
+++ b/src/newgrf.cpp	Thu Jun 05 20:54:52 2008 +0000
@@ -5783,7 +5783,7 @@
 	 * processed once at initialization.  */
 	if (stage != GLS_FILESCAN && stage != GLS_SAFETYSCAN && stage != GLS_LABELSCAN) {
 		_cur_grffile = GetFileByFilename(filename);
-		if (_cur_grffile == NULL) error("File '%s' lost in cache.\n", filename);
+		if (_cur_grffile == NULL) usererror("File '%s' lost in cache.\n", filename);
 		if (stage == GLS_RESERVE && config->status != GCS_INITIALISED) return;
 		if (stage == GLS_ACTIVATION && !HasBit(config->flags, GCF_RESERVED)) return;
 		_cur_grffile->is_ottdfile = config->IsOpenTTDBaseGRF();
@@ -5989,7 +5989,7 @@
 			if (stage > GLS_INIT && HasBit(c->flags, GCF_INIT_ONLY)) continue;
 
 			/* @todo usererror() */
-			if (!FioCheckFileExists(c->filename)) error("NewGRF file is missing '%s'", c->filename);
+			if (!FioCheckFileExists(c->filename)) usererror("NewGRF file is missing '%s'", c->filename);
 
 			if (stage == GLS_LABELSCAN) InitNewGRFFile(c, _cur_spriteid);
 			LoadNewGRFFile(c, slot++, stage);

--- a/src/openttd.cpp	Thu Jun 05 16:55:00 2008 +0000
+++ b/src/openttd.cpp	Thu Jun 05 20:54:52 2008 +0000
@@ -99,11 +99,31 @@
 
 extern void SetDifficultyLevel(int mode, DifficultySettings *gm_opt);
 extern Player* DoStartupNewPlayer(bool is_ai);
-extern void ShowOSErrorBox(const char *buf);
+extern void ShowOSErrorBox(const char *buf, bool system);
 extern void InitializeRailGUI();
 
 /**
- * Error handling for fatal errors.
+ * Error handling for fatal user errors.
+ * @param s the string to print.
+ * @note Does NEVER return.
+ */
+void CDECL usererror(const char *s, ...)
+{
+	va_list va;
+	char buf[512];
+
+	va_start(va, s);
+	vsnprintf(buf, lengthof(buf), s, va);
+	va_end(va);
+
+	ShowOSErrorBox(buf, false);
+	if (_video_driver != NULL) _video_driver->Stop();
+
+	exit(1);
+}
+
+/**
+ * Error handling for fatal non-user errors.
  * @param s the string to print.
  * @note Does NEVER return.
  */
@@ -116,7 +136,7 @@
 	vsnprintf(buf, lengthof(buf), s, va);
 	va_end(va);
 
-	ShowOSErrorBox(buf);
+	ShowOSErrorBox(buf, true);
 	if (_video_driver != NULL) _video_driver->Stop();
 
 	assert(0);
@@ -524,30 +544,30 @@
 	DEBUG(misc, 1, "Loading blitter...");
 	if (BlitterFactoryBase::SelectBlitter(_ini_blitter) == NULL)
 		StrEmpty(_ini_blitter) ?
-			error("Failed to autoprobe blitter") :
-			error("Failed to select requested blitter '%s'; does it exist?", _ini_blitter);
+			usererror("Failed to autoprobe blitter") :
+			usererror("Failed to select requested blitter '%s'; does it exist?", _ini_blitter);
 
 	DEBUG(driver, 1, "Loading drivers...");
 
 	_sound_driver = (SoundDriver*)SoundDriverFactoryBase::SelectDriver(_ini_sounddriver, Driver::DT_SOUND);
 	if (_sound_driver == NULL) {
 		StrEmpty(_ini_sounddriver) ?
-			error("Failed to autoprobe sound driver") :
-			error("Failed to select requested sound driver '%s'", _ini_sounddriver);
+			usererror("Failed to autoprobe sound driver") :
+			usererror("Failed to select requested sound driver '%s'", _ini_sounddriver);
 	}
 
 	_music_driver = (MusicDriver*)MusicDriverFactoryBase::SelectDriver(_ini_musicdriver, Driver::DT_MUSIC);
 	if (_music_driver == NULL) {
 		StrEmpty(_ini_musicdriver) ?
-			error("Failed to autoprobe music driver") :
-			error("Failed to select requested music driver '%s'", _ini_musicdriver);
+			usererror("Failed to autoprobe music driver") :
+			usererror("Failed to select requested music driver '%s'", _ini_musicdriver);
 	}
 
 	_video_driver = (VideoDriver*)VideoDriverFactoryBase::SelectDriver(_ini_videodriver, Driver::DT_VIDEO);
 	if (_video_driver == NULL) {
 		StrEmpty(_ini_videodriver) ?
-			error("Failed to autoprobe video driver") :
-			error("Failed to select requested video driver '%s'", _ini_videodriver);
+			usererror("Failed to autoprobe video driver") :
+			usererror("Failed to select requested video driver '%s'", _ini_videodriver);
 	}
 
 	_savegame_sort_order = SORT_BY_DATE | SORT_DESCENDING;

--- a/src/os2.cpp	Thu Jun 05 16:55:00 2008 +0000
+++ b/src/os2.cpp	Thu Jun 05 20:54:52 2008 +0000
@@ -145,7 +145,7 @@
 	WinTerminate(hab);
 }
 
-void ShowOSErrorBox(const char *buf)
+void ShowOSErrorBox(const char *buf, bool system)
 {
 	HAB hab;
 	HMQ hmq;

--- a/src/roadveh_cmd.cpp	Thu Jun 05 16:55:00 2008 +0000
+++ b/src/roadveh_cmd.cpp	Thu Jun 05 20:54:52 2008 +0000
@@ -1468,7 +1468,7 @@
 		}
 
 		if (dir == INVALID_TRACKDIR) {
-			if (!IsRoadVehFront(v)) error("!Disconnecting road vehicle.");
+			if (!IsRoadVehFront(v)) error("Disconnecting road vehicle.");
 			v->cur_speed = 0;
 			return false;
 		}

--- a/src/sound/win32_s.cpp	Thu Jun 05 16:55:00 2008 +0000
+++ b/src/sound/win32_s.cpp	Thu Jun 05 20:54:52 2008 +0000
@@ -24,7 +24,7 @@
 	hdr->lpData = MallocT<char>(_bufsize * 4);
 	if (hdr->lpData == NULL ||
 			waveOutPrepareHeader(_waveout, hdr, sizeof(WAVEHDR)) != MMSYSERR_NOERROR)
-		error("waveOutPrepareHeader failed");
+		usererror("waveOutPrepareHeader failed");
 }
 
 static void FillHeaders()
@@ -35,7 +35,7 @@
 		if (!(hdr->dwFlags & WHDR_INQUEUE)) {
 			MxMixSamples(hdr->lpData, hdr->dwBufferLength / 4);
 			if (waveOutWrite(_waveout, hdr, sizeof(WAVEHDR)) != MMSYSERR_NOERROR)
-				error("waveOutWrite failed");
+				usererror("waveOutWrite failed");
 		}
 	}
 }

--- a/src/spritecache.cpp	Thu Jun 05 16:55:00 2008 +0000
+++ b/src/spritecache.cpp	Thu Jun 05 20:54:52 2008 +0000
@@ -169,7 +169,7 @@
 			static byte warning_level = 0;
 			DEBUG(sprite, warning_level, "Tried to load non sprite #%d as a real sprite. Probable cause: NewGRF interference", id);
 			warning_level = 6;
-			if (id == SPR_IMG_QUERY) error("Uhm, would you be so kind not to load a NewGRF that makes the 'query' sprite a non- sprite?");
+			if (id == SPR_IMG_QUERY) usererror("Uhm, would you be so kind not to load a NewGRF that makes the 'query' sprite a non- sprite?");
 			return (void*)GetSprite(SPR_IMG_QUERY);
 		}
 
@@ -246,7 +246,7 @@
 	if (!ReadSpriteHeaderSkipData()) return false;
 
 	if (load_index >= MAX_SPRITES) {
-		error("Tried to load too many sprites (#%d; max %d)", load_index, MAX_SPRITES);
+		usererror("Tried to load too many sprites (#%d; max %d)", load_index, MAX_SPRITES);
 	}
 
 	sc = AllocateSpriteCache(load_index);

--- a/src/stdafx.h	Thu Jun 05 16:55:00 2008 +0000
+++ b/src/stdafx.h	Thu Jun 05 20:54:52 2008 +0000
@@ -317,6 +317,7 @@
 	#define CloseConnection OTTD_CloseConnection
 #endif /* __APPLE__ */
 
+void NORETURN CDECL usererror(const char *str, ...);
 void NORETURN CDECL error(const char *str, ...);
 #define NOT_REACHED() error("NOT_REACHED triggered at line %i of %s", __LINE__, __FILE__)
 

--- a/src/strings.cpp	Thu Jun 05 16:55:00 2008 +0000
+++ b/src/strings.cpp	Thu Jun 05 20:54:52 2008 +0000
@@ -178,7 +178,7 @@
 
 	if (index >= _langtab_num[tab]) {
 		error(
-			"!String 0x%X is invalid. "
+			"String 0x%X is invalid. "
 			"Probably because an old version of the .lng file.\n", string
 		);
 	}
@@ -1427,7 +1427,7 @@
 		FioAppendDirectory(path, lengthof(path), sp, LANG_DIR);
 		language_count += GetLanguageList(files, language_count, lengthof(files), path);
 	}
-	if (language_count == 0) error("No available language packs (invalid versions?)");
+	if (language_count == 0) usererror("No available language packs (invalid versions?)");
 
 	/* Acquire the locale of the current system */
 	const char *lang = GetCurrentLocale("LC_MESSAGES");
@@ -1463,7 +1463,7 @@
 		dl->num++;
 	}
 
-	if (dl->num == 0) error("Invalid version of language packs");
+	if (dl->num == 0) usererror("Invalid version of language packs");
 
 	/* We haven't found the language in the config nor the one in the locale.
 	 * Now we set it to one of the fallback languages */
@@ -1471,7 +1471,7 @@
 		chosen_language = (language_fallback != -1) ? language_fallback : en_GB_fallback;
 	}
 
-	if (!ReadLanguagePack(chosen_language)) error("Can't read language pack '%s'", dl->ent[chosen_language].file);
+	if (!ReadLanguagePack(chosen_language)) usererror("Can't read language pack '%s'", dl->ent[chosen_language].file);
 }
 
 /**

--- a/src/town_cmd.cpp	Thu Jun 05 16:55:00 2008 +0000
+++ b/src/town_cmd.cpp	Thu Jun 05 20:54:52 2008 +0000
@@ -1603,7 +1603,7 @@
 	if (num == 0 && CreateRandomTown(10000, TSM_RANDOM, 0) == NULL) {
 		if (GetNumTowns() == 0) {
 			/* XXX - can we handle that more gracefully? */
-			if (_game_mode != GM_EDITOR) error("Could not generate any town");
+			if (_game_mode != GM_EDITOR) usererror("Could not generate any town");
 
 			return false;
 		}

--- a/src/train_cmd.cpp	Thu Jun 05 16:55:00 2008 +0000
+++ b/src/train_cmd.cpp	Thu Jun 05 20:54:52 2008 +0000
@@ -3113,7 +3113,7 @@
 
 invalid_rail:
 	/* We've reached end of line?? */
-	if (prev != NULL) error("!Disconnecting train");
+	if (prev != NULL) error("Disconnecting train");
 
 reverse_train_direction:
 	v->load_unload_time_rem = 0;

--- a/src/unix.cpp	Thu Jun 05 16:55:00 2008 +0000
+++ b/src/unix.cpp	Thu Jun 05 20:54:52 2008 +0000
@@ -214,7 +214,7 @@
 	fprintf(stderr, "%s\n", str);
 }
 
-void ShowOSErrorBox(const char *buf)
+void ShowOSErrorBox(const char *buf, bool system)
 {
 #if defined(__APPLE__)
 	/* this creates an NSAlertPanel with the contents of 'buf'

--- a/src/video/dedicated_v.cpp	Thu Jun 05 16:55:00 2008 +0000
+++ b/src/video/dedicated_v.cpp	Thu Jun 05 20:54:52 2008 +0000
@@ -107,10 +107,10 @@
 	/* Create event to signal when console input is ready */
 	_hInputReady = CreateEvent(NULL, false, false, NULL);
 	_hWaitForInputHandling = CreateEvent(NULL, false, false, NULL);
-	if (_hInputReady == NULL || _hWaitForInputHandling == NULL) error("Cannot create console event!");
+	if (_hInputReady == NULL || _hWaitForInputHandling == NULL) usererror("Cannot create console event!");
 
 	_hThread = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)CheckForConsoleInput, NULL, 0, &dwThreadId);
-	if (_hThread == NULL) error("Cannot create console thread!");
+	if (_hThread == NULL) usererror("Cannot create console thread!");
 
 	DEBUG(driver, 2, "Windows console thread started");
 }

--- a/src/video/sdl_v.cpp	Thu Jun 05 16:55:00 2008 +0000
+++ b/src/video/sdl_v.cpp	Thu Jun 05 20:54:52 2008 +0000
@@ -118,7 +118,7 @@
 	modes = SDL_CALL SDL_ListModes(NULL, SDL_SWSURFACE + (_fullscreen ? SDL_FULLSCREEN : 0));
 
 	if (modes == NULL)
-		error("sdl: no modes available");
+		usererror("sdl: no modes available");
 
 	_all_modes = (modes == (void*)-1);
 
@@ -198,7 +198,7 @@
 
 	DEBUG(driver, 1, "SDL: using mode %dx%dx%d", w, h, bpp);
 
-	if (bpp == 0) error("Can't use a blitter that blits 0 bpp for normal visuals");
+	if (bpp == 0) usererror("Can't use a blitter that blits 0 bpp for normal visuals");
 
 	/* Give the application an icon */
 	icon = SDL_CALL SDL_LoadBMP(ICON_DIR PATHSEP "openttd.32.bmp");

--- a/src/video/win32_v.cpp	Thu Jun 05 16:55:00 2008 +0000
+++ b/src/video/win32_v.cpp	Thu Jun 05 20:54:52 2008 +0000
@@ -59,7 +59,7 @@
 
 	}
 	_wnd.gdi_palette = CreatePalette(pal);
-	if (_wnd.gdi_palette == NULL) error("CreatePalette failed!\n");
+	if (_wnd.gdi_palette == NULL) usererror("CreatePalette failed!\n");
 }
 
 static void UpdatePalette(HDC dc, uint start, uint count)
@@ -292,7 +292,7 @@
 			_sntprintf(Windowtitle, sizeof(Windowtitle), _T("OpenTTD %s"), MB_TO_WIDE(_openttd_revision));
 
 			_wnd.main_wnd = CreateWindow(_T("OTTD"), Windowtitle, style, x, y, w, h, 0, 0, GetModuleHandle(NULL), 0);
-			if (_wnd.main_wnd == NULL) error("CreateWindow failed");
+			if (_wnd.main_wnd == NULL) usererror("CreateWindow failed");
 			ShowWindow(_wnd.main_wnd, showstyle);
 		}
 	}
@@ -671,7 +671,7 @@
 		};
 
 		registered = true;
-		if (!RegisterClass(&wnd)) error("RegisterClass failed");
+		if (!RegisterClass(&wnd)) usererror("RegisterClass failed");
 	}
 }
 
@@ -684,7 +684,7 @@
 	w = max(w, 64);
 	h = max(h, 64);
 
-	if (bpp == 0) error("Can't use a blitter that blits 0 bpp for normal visuals");
+	if (bpp == 0) usererror("Can't use a blitter that blits 0 bpp for normal visuals");
 
 	if (w == _screen.width && h == _screen.height)
 		return false;
@@ -707,7 +707,7 @@
 
 	dc = GetDC(0);
 	_wnd.dib_sect = CreateDIBSection(dc, bi, DIB_RGB_COLORS, (VOID**)&_wnd.buffer_bits, NULL, 0);
-	if (_wnd.dib_sect == NULL) error("CreateDIBSection failed");
+	if (_wnd.dib_sect == NULL) usererror("CreateDIBSection failed");
 	ReleaseDC(0, dc);
 
 	return true;

--- a/src/win32.cpp	Thu Jun 05 16:55:00 2008 +0000
+++ b/src/win32.cpp	Thu Jun 05 20:54:52 2008 +0000
@@ -92,14 +92,14 @@
 }
 #endif
 
-void ShowOSErrorBox(const char *buf)
+void ShowOSErrorBox(const char *buf, bool system)
 {
 	MyShowCursor(true);
 	MessageBox(GetActiveWindow(), MB_TO_WIDE(buf), _T("Error!"), MB_ICONSTOP);
 
 /* if exception tracker is enabled, we crash here to let the exception handler handle it. */
 #if defined(WIN32_EXCEPTION_TRACKER) && !defined(_DEBUG)
-	if (*buf == '!') {
+	if (system) {
 		_exception_string = buf;
 		*(byte*)0 = 0;
 	}
@@ -961,7 +961,7 @@
 
 #if !defined(WINCE)
 	/* Check if a win9x user started the win32 version */
-	if (HasBit(GetVersion(), 31)) error("This version of OpenTTD doesn't run on windows 95/98/ME.\nPlease download the win9x binary and try again.");
+	if (HasBit(GetVersion(), 31)) usererror("This version of OpenTTD doesn't run on windows 95/98/ME.\nPlease download the win9x binary and try again.");
 #endif
 
 	/* For UNICODE we need to convert the commandline to char* _AND_