Possibly a virus or spyware slowing your PC?
You can place spybot and free AVG on a USB drive, additionally, you can run a complete scan with NAV (Norton Anti-Virus) Boot Disk: This will check everything BEFORE booting to windows.
You will need a reliable source computer to work from since your main computer seems to be comprimised.
Article forAVG and instructions found here:http://www.computing.net/answers/security/avg-antivirus/17758.html
Microsoft does have an official Windows 7 Support Forum located here http://tinyurl.com/9fhdl5
. It is supported by product specialists as well as engineers and support teams. You may want to check the threads available there for additional assitance and support.
Microsoft Windows Client Team