|i would suggest trying to boot in safe mode.and trying to run your av from there. then post a hijackthis log.|
Safe Mode with Networking
Restart your computer.
After hearing your computer beep once during startup, but before the Windows icon appears, tap the F8 key continually;
Instead of Windows loading as normal, a menu with options should appear;
Select Safe Mode with Networking, then press "Enter".
Choose your usual account.