--- widgets/table/e-table-extras.c.orig	2010-12-02 00:17:00.000000000 +0100
+++ widgets/table/e-table-extras.c	2010-12-02 02:34:42.000000000 +0100
@@ -172,14 +172,17 @@
 	}
 
 	#define prepare_value(_z, _cz)						\
-		_cz = e_table_sorting_utils_lookup_cmp_cache (cmp_cache, _z);	\
-		if (!_cz) {							\
-			gchar *tmp = g_utf8_casefold (_z, -1);			\
-			_cz = g_utf8_collate_key (tmp, -1);			\
-			g_free (tmp);						\
+		if (g_utf8_validate (_z, -1, NULL)) {				\
+			_cz = e_table_sorting_utils_lookup_cmp_cache (		\
+					cmp_cache, _z);				\
+			if (!_cz) {						\
+				gchar *tmp = g_utf8_casefold (_z, -1);		\
+				_cz = g_utf8_collate_key (tmp, -1);		\
+				g_free (tmp);					\
 										\
-			e_table_sorting_utils_add_to_cmp_cache (		\
-				cmp_cache, _z, (gchar *) _cz);			\
+				e_table_sorting_utils_add_to_cmp_cache (	\
+					cmp_cache, _z, (gchar *) _cz);		\
+			}							\
 		}
 
 	prepare_value (x, cx);