IMO...the problem with many malware removals is that...removal of malware files often fails to undo the impact those files have had on the system or other files in the system. It's kind of like catching a thief...after he/she has sold everything you own...the damage has been done and will remain after removal of the culprit.
Bear in mind that I am no expert on malware or anything else computer-related...just stating observations of others' problematical situations over the years that I've been participating in various forums.
Probably the best thing to try...would be a repair install of XP. Depending on your system and model, that may not be an attractive suggestion for you...but that's the way that I would go if I were ever seriously infected and had my system crippled as an effect of such.
If that fails to solve it, I'd pull out one of my backups and install it...or just do a clean install of XP.
You might want to take a look in Kelly's Korner Website - http://www.kellys-korner-xp.com/xp.htm
for something that might fit your situation (Tweaks button)...nothing to lose but a little time.
Have you run chkdsk /r and defragged the system since the malware was removed?