smss.exe winlogon.exe trojan horse

Hi All
My virus software detected a trojan horse virus in the smss.exe and
winlogon.exe files that were located in my C:\Program Files\Common Files\
Since then I can no longer log onto my MS network nor can I modify any of
the settings in 'Tools" "Folder Options" "View"
Hopefully someone can help me here.
Thanks,
--
Ranger801