Virus seems to be blocking Norton and Windows Defender

Hello...

 

A few days ago I noticed that my Norton Internet Security had stoped working. When I tried to click on Norton Icon in the Start menu, the program just didnt open and I was conducted to Norton Homepage, where I was told to uninstall Norton and reinstall again. I also noticed that my Windows Defender (Im running on Vista 32k) also wasnt working. Tough, I tried to reactivate Windows Defender, every time I restart my computer, it automatically gets unactive.

 

My next step was to run my cpu on SAFE mode. Surprisingly, Norton Icon was working there and I was able to do a Complete Sacan, but nothing really important was found. I also had checked my cpu with both SuperAntiSpyware Free and Spybot and, altough some threats were found and removed, things are all the same: no Norton, no Windows Defender.

 

Is there something I can do?