I just set up a new desktop running Windows 10 and I have it connected to a monitor that's also connected to my old desktop that runs Windows 7. The old desktop has no video problems, but the new one does. If I hover the pointer over video content that it's supposed to autoplay, the screen will go black for a second, then the video starts. What's causing this? I've checked my HDMI cables and they're connected firmly to each PC & to the monitor ports & the cables are new. I don't have a separate video card on either machine.