Windows XP Repair Install

I know it's hard to believe, but Windows can sometimes stop operating properly—even the amazing XP (note sarcasm). When this happens the instinct is often to wipe out the operating system and do a clean install. Yeah, you could do that, but before you get that drastic, try a few other options.
With Windows XP try a System Restore http://www.worldstart.com/tips/tips.php/390
Run Error Checking (formerly known as Scan Disk) http://www.worldstart.com/tips/tips.php/254
Try to repair from the installation CD. What's that? You heard me. If your computer came with the actual installation CD you can use it to repair Windows before starting all over on a clean hard drive.
A Repair Install will replace the system files with the ones found on the CD but will leave your applications, files and settings where they are. You will, however need to redo your updates. Another advantage is that any files corrupted by adware/malware will be replaced.
Before we start: it is always a good idea to have important data backed up onto disks. This is especially true whenever doing maintenance.
First, you need to boot the computer using the installation CD. You may need to change the boot order in BIOS so the CD boots up before the hard drive. Check your owner's manual to find out how to do this. If you're a novice, then I wouldn't suggest messing around with BIOS.
Next, you'll see a "Welcome to Setup" screen with a few options. You want the first one: "To setup Windows XP now, press ENTER"
So, press ENTER to start the setup. DO NOT choose the second option, "To repair..."
You'll be asked to accept the licensing agreement then it will search for any existing Windows installations. Pick the one you want to repair from the list and press "R" to start the repair.
Don't panic. Don't press any keys. It will look like a clean install, but only necessary files are being copied to the hard drive. Windows will then begin to load.
Your computer will then reboot. It will notice that the CD is in the drive—don't press any keys, let it bypass the CD.
If your installation disk came out before Service Pack 2 you'll need to go back out and get it. You should also go to Microsoft and get scanned for updates. These are removed during the Repair Install. Here's a tip about updates... http://www.worldstart.com/tips/tips.php/428
Don't forget to go back into BIOS and change the boot order back to hard drive first.
Hopefully this will get you back on your feet and running smoothly.