Are you using Firefox? If you are, and you also have Internet Explorer installed, there is a really common, and really insidious, virus that’ll constantly spam you with ad pages. I never could fully get rid of it, so I uninstalled Firefox (getting rid of Internet Explorer is almost impossible), and now am using a pretty good little browser called K-Meleon. I haven’t checked to see if Firefox or IE has solved the problem lately, though.
“good little browser called K-Meleon.”
Make a note to yourself: If you ever decide to delete this browser, make sure you save every shortcut or file on your desktop. I used this browser and did not like it. I went to delete the program and it deleted every file I had saved to the desktop.
I had that problem too. Using opera though. SUPERAntiSpyware got rid of it for me.