I know this thread is old, but it's still relevent, and it popped up in Google, so others might need it or find it, too. I was getting horrible video playback after upgrading from Vista to Win7. It happened a little in Youtube at 1080p, but it was most noticeable in Netflix. Videos looked almost like a slideshow, and the audio was super studdery and choppy. In fact, the mouse cursor movement was even choppy. Task Manager didn't show high CPU usage though ... ? So I spent 4 or 5 hours trying all kinds of things. I thought it was the video card, the video card driver, the video codec, hardware acceleration, Silverlight, Windows 7, Aero theme, multiple monitors. I just arrived at my answer -- I turn off Malwarebytes and the video plays perfectly. It's a pretty beefy computer with an i7 CPU, 12 Gigs Ram, 2 nVidia 9600 video cards, but Netflix was pretty unwatchable. Now it's perfect with MB off. Is there a way to exclude Youtube/Netflix/Silverlight/videos from MB? I don't want to turn MB off, but I want to watch videos.