A few days ago my laptop started acting very sluggish while browsing the web. Scan with Spybot S&D revealed a few infections, most of them variations of Vundo and Virtumonde. I cleaned the infection, and rescanned with Spybot, Avast!, Symantec, VundoFix (Ad-Aware keeps saying 'could not connect to service', and Malwarebytes always freezes and can't be shut off). All subsequent scans have been clean. I bought a router to hide behind, uninstalled and reinstalled firefox, and tried virus scanning in safe mode (clean). I cleaned all my temporary internet files, cookies, cache, etc., but Firefox is still buggy. It often takes a long time to to load images and videos. When I log into Facebook and try to go to my profile, it simply says "done" and reloads the page I'm on.
I am running Windows XP Professional with service pack 3.
Any help would be hugely appreciated!