I need to remove a virus that I cannot locate

Hi All

My computer has a virus... well i think it does. it freezes up alot, not matter what you do, use internet, or other programs, it freezes, and you need to hold the off button to turn it off, when I am on the internet and click on a link (like from yahoo search) it never goes to the link, it goes to spam pages, i get loads of pop ups. I have AVG and TrendMirco installed, and everytime I run a scan it removes viruses and cookies. But it wont fix the issue

can anyone help me? i would appreciate any type of help please!!!