Getting messages to download "antivirus" again!!!!!

[mommy2alex2004]

This is what my computer did a month ago when the ads were giving problems before. I went back to IE since I prefer that over Firefox and now I am getting the message recommending downloading Antivirus 2009. I tried to close the program through the toolbar at the bottom of my screen but it won't let me. The only way I can close it without clicking on the pop up is to close the program through ctrl alt delete. or restart my computer. This started about 2 days ago so I haven't been on much as a result. So far today it has happened 3 times.

I just went back to firefox but am still seeing ads whereas I wasn't before. Please figure out the problem with the spyware and the ads and I would love advice on how to get rid of the ads while browsing with firefox. I am tired of having to close all of the programs in the middle of a PM or reading a thread!