You may be suffering from this. (From spybot home page)
CoolWWWSearch.SmartKiller (v1 and v2) is a new, real ugly variant of CoolWWWSearch. When running, it will close every browser window you use to visit a large list of anti-spyware-sites, and even will close Spybot-S&D and some other anti-spyware applications as well.
So if your copy of Spybot-S&D (or the anti-spyware application of your choice) closes a few seconds after starting, or your browser closes whenever you try to visit an anti-spyware site, check our CWS.SmartKiller removal utility on this
Try downloading the CWS.Smartkiller at a friends house, work or at a internet cafe. Might give a fighting chance to get your system back. If you really can't get rid of it, try format your hard drive and reinstall windows. (I hope you've been backing up!) No need to buy a new machine.