Computer or vid card problem?

Hello! Some times when I try to run netflix or a game, the screen gets these red grid pattern imposed over the images; across the whole screen with these little rectangles. If I go into my display settings and switch it from 16mb to 32mb OR vice versa it the red blocks go away. I have to do this in my display settings most of the time. I don't think this is a monitor problem. Is it my card or a driver problem? I have a MA in Intl Relations but know almost nothing about pc's so please explain in layman terms. Thanks for the help!!