I often get asked, usually in the forum, if there's a way to reinstall Windows XP without having to erase everything and start over. Lucky for all of us there is, and it's pretty easy as long as you can dig up your Windows CD.
It's called a Windows Repair Install. A repair install is a way of installing Windows XP right over top of your existing Windows XP installation, repairing any damaged operating system files in the process. The best part is that all of your other programs and any other saved data on your computer is left alone during the process.
Repair installs don't always fix every problem - sometimes starting over from scratch by wiping your computer clean first and then installing Windows (a process called a clean install) is necessary. For many problems though, reinstalling Windows XP with a repair install is a safe, effective way to solve serious problems with the operating system.