computor restarts itself

i recently downloaded a minigolf game......after an
antivirus update it was determined to be infected. i
dumped it and now my compt. will cut off and restart on
its own. usually when you open or close a program. i
opened an error report and saw C:\ WINDOWS\ Minidump. i
did a search for the file and deleted it. but it keeps
coming back!! everything works good them click its off
again. do a search.... minidump's back! plz help! im out
of ideas. thanks