My computer is acting odd.

Hello,

Like I said my computer has been acting odd lately, it's started out with just little things like a pop up telling me a program is corrupted yet that same program is working fine when that pops up, then I went to scan my computer with my anti-virus like I do twice a week and it wouldn't work. Then I like on a link to like any website and I get redirected to a pop up but I have pop blocker, now if I click on something like some video hosting my comp crashes. And while I'm working on the computer a streaming radio just starts, I've figured out that my comp is running IE as a ghost program and once I stop the process with task manger it stops, I don't use IE I'm on firefox. Now my roommate user is odd no backround will appear and the IE shortcut won't be deleted from her desktop, yet mine is acting fine other then being a little slower then normal and firefox tends to freeze more then it should.

I'm running windows XP with Avira antivirus, I've added AVG 8.5 to scan then comp but no viruses have popped up, I'm worried that this could be the explorer.exe virus, I'd like to know I'm trying to back up anything important just in case it's something else.

by the way it's a recovered system.