cavekas
known_criminal and snowmonkey are giving you good advice, but you might try looking for a virus first, since your sympton is similar to those caused by some of the recent virus outbreaks like lovesan and blaster. The following website has a good program for free which will scan your computer and also remove the virus if you have it. Just look for "download Stinger." Otherwise, the other guys have already given you your only recourse.
http://us.mcafee.com/virusInfo/defau...al/Stinger.asp
Regards,
TAB