I Can't get rid of Antivirus System Pro!! HELP ME?

Okay, so last night, I was working on my English paper. while doing so, some crap just starts popping up including spam from Antivirus System Pro begging me to install it. Obviously this thing is a scam. Well anyways, it wouldn't let me open any files because when I tried, a security error just popped up. I couldn't use the internet, or get into the registry edit, and I couldn't open task manager. (im typing this message from a different PC). The only way I can open anything is if i spam click them as soon as i log on before the virus boots up. So far, I already opened regedit and deleted the file AvScan and its subkeys. The problem was still there, and when i logged off then logged on, the AvScan folder and all its sub keys reappeared!! I dont know why. Second, I ran the norton virus scanner and the malware bytes anti malware program. It just finds the same 1 infected file, the AvScan folder in the registry. Well anyways, i didn't feel like dealing with anything, so i reinstalled windows and lost all my data which wasnt that bad. then, i installed windows, came on, and the problem was STILL THERE!!! HOW DO I GET RID OF THIS STUFF!!!!!!!!!!!!!!!!!!!