Windows XP System Restore
Windows is well-known for having driver and .dll conflicts, as well as all sorts of software that causes problems with your computer. Luckily there’s a System restore feature that can return your computer back to a known working configuration, as long as you’ve created a restore point.
Note that some software installations will create restore points automatically, but you should run it manually before installing any questionable applications. (Or better yet, don’t install questionable applications!)