Windows 7 64-Bit & Youtube Problem

Hey guys. I just bought Windows 7 Home Premium 64-Bit, and when I went to watch a YouTube video full-screen, the screen went full, but it was split with a diagonal line from the bottom left to the top right, with one-half being black and the other half being white. Does anyone know how to fix this?

im using ultimate and I have no issues.

EDIT: Nevermind, it just turns out that my flash player was out of date, but I had to take it to Future Shop to get them to install it because it didn't want to for me. Something about Admin rights, when I'm an admin.