My display will freeze intermittently(mouse cursor still moves) for a few seconds, then goes black for a second then comes back. It's doing it more often now and sometimes will do it over and over so I have to power off. When it starts doing this, I will get an error beep from the tower. I thought maybe video card. I noticed it seems to do it more when I'm web browsing quickly in multiple windows so I thought maybe ram but that may just be coincidence. Please help. Thank you.