Read http://forums.majorgeeks.com/showthread.php?t=35407 and make sure no other pests are on the machine. A pass of IEFIX (find with google.com) would be my first repair item.
I have a gateway that had win98se on it and I upgraded it to winXP SP1. I had adware/spyware on it ran adawareSEpersonal & Spybot S&D. installed NAV2003. Did updates and scanned for viruses, found blaster and ran the tool to fix it, then win updates.
now when I try to search the web I cannot do anything. I can bring up say Yahoo, click "mail" the sign in as soon as I press enter the screen goes right back to my desktop. no browser to be seen. Any Help on this matter would be appreciated. It does the same with hotmail and other web sites.