Bug 270557 : downloads fail silently if the default download path is invalid, e.g. leads to a removed drive, patch by Son Le <son.le0@gmail.com>, r+a=mconnor

toolkit/mozapps/downloads/src/nsHelperAppDlg.js.in

@@ -245,7 +245,7 @@ nsUnknownContentTypeDialog.prototype = {
     
     validateLeafName: function (aLocalFile, aLeafName, aFileExt)
     {
-      if (!aLocalFile)
+      if (!aLocalFile || !aLocalFile.exists())
         return null;
 
       if (aLeafName == "")