I'm using Maya 6.5 and when I first started using it on my computer everything worked fine. Now, for some reason all the four view windows are completely gray when I start it up. Sometimes I can zoomed way in on the perspective window and find the grid but the other three views are impossible to find the gird or any of the models. When I do find the grid or the object I'm modeling in the perspective view it disappears when I zoom out just a little bit and I have to be zoomed in really far. It wasn't like this before and I'm not sure what caused it to stop working.
If anyone knows how to fix this please tell me.

Thanks
Alex