I thought I posted this yesterday, but....
Try SuperAntispyware or MalwareBytes Anti-Malware first (from safe mode if you want) and see if they work. I know MBAM will install/update from safe mode unless you've got a rootkit preventing it.
If neither of those two will work, then I'd recommend the following:
1. Download ComboFix onto a USB flash drive from another computer.
2. Boot into SAFE MODE or regular mode (if required) and uninstall your anti-virus software. Yes - remove it. Reboot.
3. Clean out temp files and registry with CCleaner. Save before making registry changes each time until no more errors.
4. Reboot computer in Safe Mode with networking (hopefully you can attach the PC to a wired/ethernet connection vs. wireless because some wireless will not work in safe mode and you NEED internet).
5. Copy combofix to desktop and launch combofix and allow it to do its thing. Follow screen prompts and do what it says to do/NOT to do.
6. When computer has restarted for the last time, check things out.
7. Turn OFF system restore to flush out anything left
8. Reinstall anti-virus and MalwareByte's Anti-Malware. Run a full scan using each (at different times) and see if things are clean.
9. Turn System Restore ON.