hell, reading ur title, i thot that microsoft had introduced spyware !
(like the sony rootkits issue).
run d ms anti-spy in safe mode.
use it (or ccleaner from
www.ccleaner.com) to clean ur internet cache/tracks/pc junk.
use it to retore ur browser settings.
disable auto-update feature.
reboot.
u said u get ads popping. do u mean pop-ups ? in that case u need a good pop-blocker. install google search toolbar. it will help u. in case u have sp2, activate its popblocker too.
if u want to block ad site. download 'hosts' file from
http://www.mvps.org/winhelp2002/, and put it in ur C:\WINDOWS\system32\drivers\etc.
it will stop faltu crapware sites from opening.
if stl all fails, post ur hijackthis logfile here.