Photoshop is split-screening & freezing causing me to lose work? "Support" did not help with this.

I have Photoshop CS5 and the problem started about a week ago.

I opened an image, got 3/4s of the way through it, and the computer screen "split into two" and froze. Causing me to shut down my computer, entirely, and lose an hour and half's worth of work. I shut my computer down, completely and did a full system reboot, and tried again. This time I didn't even get a full step into editing before the same thing occured.

Worried, I had contacted Apple Support because I thought it might have been something with the video card. After putting me through various tests, all of which turned up clean, Apple said it was something that showed it wasn't with Mac, it was with CS5 itself (or at least with Adobe's Photoshop application). They told me to try calling Adobe. However, they only have certain hours, so I tried chat support - which was hysterical, becuase they kept sending me over here to the forums. (Apple's support takes much better care of their customers, I've noticed, at least when it comes to full "chat support".) Anyways, I had given this computer a break for a day or two, completely shut off. Today, I turned it on, and the same thing happened. Opened a .Raw image, got it into the Photoshop main screen, got a step into editing, had the computer screen split again, and freeze.

I would greatly appreciate anyone's help with this subject. I have been unable to work for about a week, which is completely devastating to someone who runs their own business. Advice, or thoughts?