I started getting a load of skype looking popups and yellow banner adverts on every web page I visited and on every browser I used. I uninstalled some suspicious 'webcam installer' software that my antivirus wasn't picking up and which I hadn't installed myself and that fixed the problem temporarily. It started again recently (I'm still trying to figure out which website not to trust) but removing another webcam program only fixed the issue in Opera. Reinstalling Chrome didn't fix that issue but clearing browsing data did. Now it's started popping up in the Steam browser, even in safe mode, and reinstalling/clearing cache/resetting router to factory defaults/running every antivirus under the sun hasn't helped. It's not affecting any other browser so I think I'm close to getting rid of it?