Your Windows installation might be hosed by spyware/junkware. I would follow the steps suggested by the members here to see if it works. If you still get messups after the Windows reinstall, you will probably need a mobo replacement. Mobos new cost a left nut.
You MAY be able to get used mobos off Ebay, but the amount of labor needed by a Do-It-Yourselfer that isn't familiar with IT may not make it worth it. Let us know how things go.