pop ups etc arrgghh

Hi, ive a problem with advertisement popups, new pages opening and words being highlights on forums etc

Ive run the pc in safe mode and done full scans using th following programs

adwcleaner
mcafee
hitman pro
malwarebytes
superantispyware professional

None of them are picking up anything..

Soon as i start the pc and browse the internet the same problem continues..

Theres nothing in program files that shouldnt be there

Any advice/help would be appreciated. Cheers