Okay first and foremost:
1) an up to date firewall
2) an up to date AV
3) an up to date Malware program (I use Win Defender, spybot Search & Destroy and Ad-Aware.
4) Run a total system check, Let it run all night if you have to
and if still nothing works good ....
5) Re-install windows (preferably from a formatted drive)
6) Repeat 1 - 4
7) Make sure (now that you have a clean PC) you get the latest drivers for at least the Graph Card, if you did a format, you should have checked the net for all updated drivers available, this includes chipset drivers etc etc
8) I know that you already know all these things Ube, but take it from a paranoid pc user, that reformatting the system drive is the ONLY sure way of getting rid of any infections .... yes it takes time! but you will be surprised at the speed that windows will run at, after you get rid of all the bad stuff AND all the left over bits and pieces from programs you have uninstalled over the year.

And you know what? it works a 100 % of the time <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />

Mea Culpa's Demesne Note; artwork for Avatar courtesy of NWN and CEP Old Elven Saying: "Never say Never if you're gonna live forever!!!" "I didn't do it, it wasn't my fault"