My default browser is Firefox, but in the last 2 weeks or so Internet Explorer spontaneously pops up with all sorts of advertising sites. Each time I run Ad-aware it removes multiple files and ditto for Spybot. AVG heals several viruses each time it runs. I've run all 3 programs every day with the same results, but the problem just keeps coming back. I've attached the hijackthis log and would appreciate any help.