I cleaned this computer of malware and viruses by using the following programs: Kaspersky TDSSKiller, RKill, Malwarebytes Antimalware, RogueKiller, AdwCleaner, Junkware Removal Tool, Kaspersky Rescue Disc 10. Then ran Tweaking.com Windows Repair. Installed Adblock Plus to IE and tested. No more popups or ads at the top of google search site. Computer seemed clean. So gave the computer back to the customer. Now after a 4 days, he's returned the computer back to me, with the same problem. This time I checked programs and features for recent programs installed, and removed Utorrent, PC Cleaner, FastCleanPro, and other malicious programs.
Once again the computer seems clean. How can I tell if its really clean and this stuff won't come back again?