Fixed one file ROM file error message.

git-svn-id: svn://svn.code.sf.net/p/stella/code/trunk@2724 8b62c5a3-ac7e-4cc8-8f21-d9a121418aba

src/gui/LauncherDialog.cxx

@@ -498,7 +498,7 @@ void LauncherDialog::handleCommand(CommandSender* sender, int cmd,
         if(!romnode.isDirectory() && !romnode.isFile())
         {
           instance().frameBuffer().showMessage(
-            "Invalid file or doesn't contain any valid ROM files",
+            "Invalid file (check file size and/or contents)",
             kMiddleCenter, true);
         }
         // Directory's should be selected (ie, enter them and redisplay)