Occasionally your Windows XP installation can become completely hosed. Be it by spyware/viruses, “accidentally” deleting system files or messing with the registry, there are lots of things which can potentially go wrong.
In these cases it the fix might be as simple as a repair of your XP installation. If you have never done a repair, this might sound to difficult to do, but it really isn’t. With this guide to repairing a Windows XP installation, all the steps are laid out. Additionally, there are several clearly marked warnings to make sure you avoid any pitfalls.
If you are unsure of whether or not to repair your XP installation, make sure this is the appropriate step to take before you start. A good place to post questions to (of course) are the PC Mech Forums.
Note: before doing any major work on your OS install, make sure you have your important data backed up.