Sorry Caperjack only seen your post after I sent mine.....lol

If you are having trouble with a video in WMP then I would download VLC Player. Works great

After scanning for viruses and spyware I would get rid of McAfee and install a free antivirus like AVG or AVAST or AVIRA. McAfee is a memory hog and the free AV programs do not use as much memory...

download magic jelly bean and it will tell you the serial number of your XP installed on the machine

in ms config shut off everything other than your virus scanner.

Have you ran MSconfig and removed all unnecessary start up items from the start up tab? That would be the first thing to try if you have already ran AV and spyware software. Which Spyware program...

Have you tried starting up in safe mode?

Try a free program called Glary Utilities. Install it and just run the one click maintenance. This might help your problem. I've used this on many computers with the same problem as yours and it...