What SAF Version do you have installed?
Please make sure you have the latest SAS, if not download them here:
Free Edition users click HERE for 6.0.1232
Professional Edition users click HERE for 6.0.1232
& run a scan
That (may) Have fixed the problem, if not:
Can you go to (x86) HKU\S-1-5-82-3006700770-424185619-1745488364-794895919-4004696415\SOFTWARE\MICROSOFT\WINDOWS NT\CURRENTVERSION\WINLOGON# in your windows file browser and post a screen shot or copy and paste the names of the registry files for me?
You can try unlocking the file with unlocker and then re-scanning with SAS, it should hopefully work after unlocking the registry file.
Unlocker Direct Download: http://www.majorgeeks.com/index.php?ct=files&action=download&
About Unlocker: http://www.majorgeeks.com/files/details/unlocker.html
Remember to use 'Custom Install' and uncheck all the boxes (unless you want them) when installing unlocker as it will try to install freeware programs.