MacBook Pro Won't Start - Gray Screen

Recently, I was opening a Microsoft Word document, and my MacBook went to a gray screen. I held the power button to turn it off and I restarted. I heard the typical Mac startup sound, but the system went to a gray screen again. I can't do anything to boot up the Mac beyond that. I've tried booting into safe mode, single-user mode, Recovery mode, and resetting the NVRAM/PRAM. Is there anything else I can do? The computer is running the latest version of Mountain Lion. The install disc I have is either Leopard or Snow Leopard, so I'm not sure if that would help. Thanks in advance for your help.

I should also note that the laptop is no longer under warranty.