Do you know that your floppy and CD rom drives work properly? e.g. can you boot from floppy and cd?
If they work fine, it might be best to re-install the Operating system. You will need to backup your information first though. Do you know anyone who would be able to remove your hard drive and copy the contents onto another machine by plugging it into theirs? If not you might have to go to a shop :mad:
Anyway once you have backed up, wipe the hard drive and re-install using your CD's. Try to ensure that you have as many of the driver disks as possible before you start. Also go to device manager and take a note of your devices - graphics, sound, network drivers etc. This way if you don't have the disks you at least know what drivers you need to download.
Sorry I can't be more help with this problem, as I said earlier, I think this might be caused by Service Pack 2 problems but I don't know the solution :confused: