last night an ad appeared for anti virus stuff and my husband clicked no maybe ten times to no avail. He turned off and unplugged. Upon turning back on, nothing. windows xp. hp
teena3bullbats, can you boot into safe mode? Sorta round-about way to get there, but... Have a friend (on another machine) download 'Superantispyware' (free @: http://www.superantispyware.com/) and burn it to disk.
Run it in safe mode and it should get rid of your nasty. There may well be a simpler way, but I don't know it.
HTH.
Ed in Texas.