I believe that the above posters are absolutely right. I have never been very computer literate, and my previous computer was a Gateway that came with a restoration disk which afforded easy reformatting. Whenever I experienced a problem that I couldn't, otherwise, counter from, I would format in a heartbeat. I had really become known as the format king . I can honestly say that I had formatted that computer no less than eight or ten times in the space of a year - with no seemingly ill effects from it. In fact, I have often heard (in very knowledgable circles) that defragging a harddrive should be more of a toil concern that reformatting.
But just for the sake of it, I thought to include something that I found (just tonight) in Dan Gookin's 2nd edition of Troubleshooting your PC For Dummies book.
I do believe in that concept of not reformatting the drive, but software glitches, incompatiblity, missing files, or corrupt software/drivers in the long run forces us to do just that.