--- a/misc_gui.c	Mon Sep 06 21:47:12 2004 +0000
+++ b/misc_gui.c	Mon Sep 06 22:46:02 2004 +0000
@@ -457,6 +457,7 @@
 		TileHighlightData *thd = _thd_ptr;
 		TileIndex tile = thd->redsq;
 		thd->redsq = 0;
+		_switch_mode_errorstr = INVALID_STRING_ID;
 		if (tile != 0)
 			MarkTileDirtyByTile(tile);
 		break;