Some people mentioned to update your video drivers. For that matter, you might want to check if the proper video drivers are even installed.... you may be running generic software rendering drivers. This is common if the computer wasnt' initially setup correctly.
If you're on windows 7:
Click start and in the search box type: "Device Manager"
Look under display adapters and post here what is listed. It should say something like a video card name, or "Intel 3D Graphics Display Driver" or something similar.
If it says something like "Generic PnP Display Adapter" or "Windows Display Adapter" or something like that, it could be your problem. (I'm not sure what the generic adapter is called these days)