Since 2 weeks i encounter pc problems.. get unwanted pop ups - even after downloading McAfee Virusscan and security 8.0 on my pc and yet it doesn't work well!! :o(

Today I again got warnings on this screen from BK, that my pc has dangerous spyware etc & I have no idea where that comes from... looks like from BK, because not a new browser pops up, but right on the screen here... if i click on Back i get back on the previous screen..

Anyone knows whats going on or what i should do? I should better re-install Windows 98, right? But if someone here has the time, please advise me or write a path for me what to do first, second, third.. I really need help!!

Could it be that by playing these games the memory gets full?

Thanks so much in advance..