You may encounter "Unspecified error" message throws by IE after you click on Cancel button , when IE warns that you navigate away from an unsaved page. This error happens in both IE 6 and IE 7. Solution to this problem is to put handle the error and prevent them to show on user's browser. Put this codes below into your .aspx page.
window.onerror = UnspecifiedErrorHandler;
function UnspecifiedErrorHandler()
{return true;}
