I got something similar to Antivirus System Pro on my computer called Advanced Virus Remover a few weeks ago. I tried Malwarebytes and AVG, but they both didn't work. Neither would System Restore or even the internet. I had to ask Dell for a Windows XP Installation CD and completely reinstall Windows XP on my computer. It sucked, all of my programs were gone including No Limits.
I'm guessing backing up all your files on a CD and reinstalling your computer is the only way to get rid of it completely.