The reason for this is that the malware is rooting into windows processes and the registry so even when you remove the files they are recreated when the PC is rebooted.
I would try the above link and use combofix but also i would submit a HiJackThis log to someone qualified to make sure.
If you don't already have it you can download it here: http://www.download.com/Trend-Micro-Hijack...4-10227353.html
NOTE: Only use ComboFix if you are confident with what you are doing.
Split away from posting in another topic ~~boopme
Edited by boopme, 09 June 2008 - 02:23 PM.