Well, reistall the ****** with a fresh XP or whatever your choice of OS is . . .
Might be a bithc the first time, if you've never done something like this before - I did my first with my 80486 from IBM back in the days (yes I'm not just old, I'm gargantuan, ancient and dusty) and I can tell you this much, it's a LOT easier now . . . Basically you're required to be able to read and understand English (or whatever language you're installing through) and use a mouse
And once you've gone through the painstaking work of it once, it's even easier the next time . . . All you need is some drivers, copies of the software you're using and some spare time (say 2 hours max) . . .
I usually format the disk first, after having repartitioned it, to make it totally fresh . . .
In fact you can probably fix the problem by simply doing a repair - boot up from the XP cd and choose repair . . .
If that don't work, try upgrading to the newest drivers for your various hardware and well, otherwise the above reinstall should fix anything . . .
Alternatively sell it to an idiot and buy a new one