also, check what programs are u running. run msconfig and see what's in the Services and Startup tab. if u see a suspicious one, terminate it and see if that was it. be carefull to not terminate a OS related one (usually, if it's made by microsoft, don't check it off)
I wouldn't go running around it the registry just like that! Nor would I turn off services willy-nilly. You could potentially end up worse off.
Check your services against
this site's guide (a guide for Win2k is also available).
Give your system a thorough clean with
Spybot and
Adaware to remove most spyware.
Have a flick through add/remove programs, and kill anything you don't need. If there's a process you're not sure about running in the background (ctrl-alt-del task manager), google it to find out what it is doing.
Clean out your browser's cache, and remove all files from your temp directories (C:\Windows\Temp and C:\Documents and Settings\Username\Local Settings\Temp).
Got an up to date virus scanner?
Download one for free.
Download the latest drivers for your various components. Visit Compaq's site first.