The latest version of GarminExpressInstaller -- which the User is forced into if they don't have the most current version -- hangs without completing on the Cleanup step.
I am sorry about the trouble updating Express. If you are still having trouble, I would recommend following the steps in the FAQ Why does Garmin Express fail to install to my Windows computer?.
If the steps in that FAQ do not solve the problem, it would be best to contact Product Support by phone.