Sounds a bit strange that, as on every PC that I've used maya on (including some really rubbish spec Pc's with internal graphics cards) theres never been a problem in rendering as creating the image is a software process not strictly a graphics card one (as the card just displays what the software says and the iff image codec is included in the maya software)

One thing to give a go would be to import the scene into a new scene and give it a go from there, sometimes when I have severe problems that seems to sort things out?

Do you have this problem with other scenes, say just create a new scene and then create a nurbs sphere and just render that to see if you get the standard gray lambert sphere?

Cheers