Index: frm/frmQuery.cpp
===================================================================
--- frm/frmQuery.cpp	(revision 8227)
+++ frm/frmQuery.cpp	(working copy)
@@ -1451,7 +1451,8 @@
     wxUtfFile file(lastPath, wxFile::read, modeUnicode ? wxFONTENCODING_UTF8:wxFONTENCODING_DEFAULT);
 
     if (file.IsOpened())
-        file.Read(str);
+        if (file.Read(str) == (size_t)-1)
+            wxLogWarning(_("The selected file could not be opened because it contains characters that are not valid UTF-8. Please try again with the 'Read and write Unicode ITF-8 files' option turned off."));
 
     if (!str.IsEmpty())
     {