probably a virus...unless you have overclocked anything.
run scandisk, and go to <A HREF="http://housecall.antivirus.com/" target="_new">http://housecall.antivirus.com/</A>
and run the scan on your computer....see if it finds any viruses. if it does, see if it can fix it. if it cant, then try to delete the files, (unless they are part of windows or something)
also, have you changed anything recently?????
because change it back if you did...and see if it goes away.
-Live, Learn, then build your own computer!-