Random full system hang

My computer will entirely freeze while playing the actual game. Not just the FFXIV process, I'm talking the whole machine. Everything. I can play Battlefield 3, Assassin's Creed 3, Dishonored, Firefall, EVE, WoW, etc all without a problem.

This game continually hangs my machine. It is totally random. It can happen after 10 minutes or 10 hours, during a cutscene, in an area with no people or a lot of people. My frame rate never stutters, my computer doesn't lag or anything - it'll just be full system failure.

I'm using the STABLE video drivers. I have an ATI Radeon HD 7850. I tried the beta drivers and still had the same problem.