Kylie

All of a sudden I am experiencing pop up web pages, mainly adverts for virus, spyware removals etc. I run Windows XP with Windows Defender for spyware. I also have installed AD-Aware, with AVG for virus protection. I have run all 3 of these, scanned several times, nothing has been found, just a few spywear traces which I removed, but these jolly pop up pages keep coming up. Can anyone help me please????