Do you mean to say you reinstalled Windows?
Litro had similar problems.. try disabling any Antivirus software, and give it another go.
To help me help you. Go to Start -> Run ->type 'msconfig'
Go to the startup tab and post the name of the startup items within this tab.
This will give me a good indication of what is running.
NOTE: DO NOT make any changes in system config if you don't know what your doing please
-Dieselbrad