My computer contracted the XP anti-virus virus a few days ago. Which was immensely frustrating. Neither Mcafee, Avira, or Avast would pick it up, and I was too much of a chicken to delete the program files and remove it manually. However, I did plug in a registry code I found online, and it left me alone. Shortly after, Avast found a virus and fixed it. But now my computer won't let me open any programs, or anything on my control panel. Which is worrying. Any ideas what happened/what to do?

Any help would be greatly appreciated. :)