Can someone help me out, I got virsus

Okay so I havnt had any anti virus programs for a few weeks, and I think my computer fulled with vrisus now, I got avg 8.0 free, but when I go to update it, it will say all the avg pages cannot be found, but I try them on another computer they work, So something blocking them sites to work, My spy bot search and destroy program wont open up either, Also the mozzila will crash all the time and Ill get flooded with alot of Intert Explore pages opening up. Also I get heaps of pop ups, I was wondering can someone give me a link to an alternvity free antivirus program or any help.