spy sheriff is the most difficult "virus" i haver had in my PC. It took 1 day to remove it. I advise installing kaspersky anti-virus after you fix the PC.
Btw, i had installed Norton when the spy sheriff attacked... and in 5 seconds Norton was OFF - shitty anti-virus.
some topics i used to fix the PC:
http://help.lockergnome.com/index.php?showtopic=35658
http://www.dslreports.com/forum/remark,14747935
hope it helps!