Game (or video?) crashes in Arma3 Alpha

[Lucky44 13]

Since I got the game on March 5, I've had seemingly random crashes.

WHEN: seems random; most frequent was 3 times in 30 minutes. Typical is about every 2 hours. Longest stretch w/o crash was probably 3-4 hours.

WHY: Not sure.

SYMPTOMS: I run two monitors (one for the game; see specs below), and usually each screen goes gray or light blue with black stripes, but it varies. The hard drive LED activity light continues to blink, and the system fans keep turning. But nothing from the keyboard has any effect, including ctrl-alt-del and alt-tab. I have been in TeamSpeak when it's happened, once, and I think that TS worked for a few seconds longer after the screen crash.

SYSTEM: details can be seen here. My video drivers are up to date. System has never had this crash with any other game, and it continues to run Arma 2OA fine.

Notes: I tried checking my temperatures (GPU and CPU cores), and nothing extreme was going on. My GPU was up in the 60C range, but not over 70C. I've run it close to 80C w/o problems in other games. I also tried taken my overclocking down from 4.5ghz and 1666mhz (RAM) to stock (3.5ghz and 1333), but that didn't change anything...still had same crashes.

Obviously, this could be a game issue, or it could just be something wrong with my GPU/card. Any suggestions? Anyone else seen this?