Have you tried creating a new user account and giving it full admin rights. Then log in with that new account and clean places such as C:\windows\temp. Also clear all internet temp files via internet options in control panel.
Lastly go in to your start menu. In the Run box (or search programs and files) and type in there %appdata% and hit Enter. Once in there go in to Local\temp and clear everything from there also.
Don't worry if it says it can't clear one or two files. These are usually virus program log files it needs.
After that do a reboot. Then once back up log on with your usual account and delete the temp user accout you created before. See if that lot helps.
If you have any luck with this please post back and let us know. Good luck