Sounds like you have Spyware installed. First thing I would do is go and get Ad-aware 6.1 (I think) and also Spybot SD and actually Hi-Jack This is pretty good. A shame we have to install this crap just to keep porn etc out of our machines... All can be found with a simple Google search. Also, do a ctrl-alt-del and see what processes are running. Again a Google search will tell you what each service is by searching their names. Go to administrative tools, services, and see what’s running. Messenger can be disabled, that will stop some popups thru the messenger service. This is not MSN Messenger but a built in administrative messenger
After you get you computer back from the spyware, (your start page has been hijacked and there is some type of scripting running to prevent you from changing it back. I was hit with one of those damn search toolbars from a redirect and it actually disabled Panicware popup stopper which I also recommend.) Check add/remove programs from the control panel, see what is installed and get rid of whatever you don’t use. Be careful of course. Adaware and spybot will find most but you will have to follow up in add/remove. Stay off porn sites, but I have got spyware from legitimate sites too. CNN, Fox, ABC etc all drop tracking cookies on us. Run the Windoze XP firewall! It ain’t the greatest but it helps. Run msconfig and see what’s starting up. I guess go from hereâ€