Question : Error installing sql express upgrade

I have tried installing sql express upgrade to 10.50.1600 from 10.1.2531.  I have tried 4 times removing all files in the last try.  It continually stops on sql core shred cpu32 action install files copying new.  This hangs and does nothing for over 30 minutes.  Any idea what files I might be missing?

Answer : Error installing sql express upgrade

Do you mean you are trying to install SQL Server 2008 R2 Express from:

http://www.microsoft.com/downloads/details.aspx?FamilyID=c772467d-e45b-43e1-9208-2c7b663d7ad1&displaylang=en

Make sure you have the pre-requisites installed properly to get it installed without any issues.
And use Windows Installer Cleanup utility to uninstall incomplete installations..