Try logging in to safemode and see if you can run any of the scans from there. To access safemodem gently tap F8 while your computer reboots and then select safemode with networking from the list.
From there I would try to install, or update, MBAM and run it. Delete what it finds and then I would install and run SUPERAntiSPyware
. Yes, it's limited in its capability in safemode but it's starting point.
After that I woudl update the antivirus software you a re using and run a full scan with it as well. Log back in via the regular Windows mode and run all of the scans again. Get rid of what they find.