Unable to login as user

Hello,
Hoping that someone can give me some help on this.

My computer will boot up, and come to the logon screen. When I click on my user profile, its says "logging on", the

screen flashes, then it immediately says "logging off", then "saving user settings". It remains at the logon screen.

If I try to logon in safe mode, I have the additional option of Administrator, but get the same result. "Last known

good" configuration does not help either.

I cannot get into windows at all! Please help! Prior to this happening I had run the most recent version of Ad-Aware

and rebooted several times without problem'