You know the drill - corrupt OS, Virus, screwed up registry, etc. The solution usually boils down to reformat and reinstall, unless ... You regularly image your OS install. Use something like Acronis (costs $50), though there are "alternative" ways of getting it. Schedule it to image (I usually do once a week, and keep up to four images covering a month), invest in another hard drive or usb drive (these are dirt cheap now), and should the situation arise, you'll be back up and running in less than an hour. These are essential if you like to update your hardware regularly like myself, but at the very least, makes the whole format and reinstall ordeal much easier to deal with.