My D2 LOD cinematics don't seem to work...?

I'm running windows 7 64-bit, 4Gb RAM, 2128 MHz processor speed, intel HD Corei3 graphics card (p.s. I have no idea what any of that means but i figure you computer buffs may find that information relevant to the issue). When each cinematic initializes, it will play for about .2 seconds - so you get to the 5th frame or something - and then it stops there. The audio continues but the screen is stuck at the beginning. I've tried it without compatibility modes, with Windows XP compatibility modes, desktop composition turned off, etc. I've tried adjusting the screen resolution and re-running the video tests. All to no avail. I can't imagine my video card isn't sufficient because I can run other programs of much higher caliber with relative ease, and even my old Windows XP with worse hardware has run it. I've searched Blizzard and google searches for answers, also without result. Everything else runs smooth as ever. Any ideas?