My course of action when working with clients' computers:
All free btw...
1. Install avast! and run a boot-time scan
2. Install and run Malwarebytes Anti-Malware (MBAM)
3. Install and run Lavasoft's Ad-Aware
4. Install and run Spybot S&D
5. Do another avast! boot-time scan
If you've still got problems try VundoFix and also use ATF Cleaner to clean out any nasties hiding in temp folders.
If you've STILL got problems, reinstall windows.
P.S., I'm on the go, so I couldn't post links, but googling any of these should take you right to the sites.
Zac