My computer says it has a virus, but when I run tests there's nothing wrong. What's up?

It also won’t let me click on my AVG or open any kind of virus program… which makes me suspicious, but when I did a virus removal thing (online, since it wouldn’t let me download anything) it said that nothing was wrong.

Also, IE keeps opening with this link to a virus removal program that I would have to buy for $80 dollars…

Is there anything I can do?

update: now it’s sending me to porn sites… i have no desire to watch old ladies get jiggy with it. .___.