I started having random ads appearing in IE a couple of weeks ago. The McAfee scan says all clear, but there is an IE add-on called 'Browsseo22ssaave' that I am not able to disable through IE. I have read this is adware but there is not much info on the web about this virus.
I also ran a HiJack This scan and there is a registry entry with the same name that refuses to be deleted. I ended up finding the directory with the same name and deleting it. I am not sure yet if this has fixed the problem as the add-on still appears in the add-on manager. This is a brand new Acer laptop running Windows 8 (yuck).