I'm running Diablo 3 (start edition, digital download) on the following:

Ubuntu 12.04 64-bit (stock Unity, Gnome, etc; kernel version 3.2.0-29-generic)
Wine version 1.5.11 (base, from Wine's PPA, game started with setarch i386 -3)
Intel i7 920 CPU nVidia GTX260 with driver version 295.49 ("post-release updates" entry within the proprietary drivers tool), dual monitors
6GB RAM

Every so often (and what appears to be at random), the game video will freeze up. I can still move the mouse, and it reacts to ctrl+alt+f2 to drop into text mode, but I can't get back to the desktop (which means I can check terminal to see what's going on after launching from terminal, especially since even in windowed mode, the secondary screen gets shut off by the game), and I can't continue to play the game. In order to get it running again, I have to restart lightdm, then relaunch the game (or, in a couple of rare cases, I had to restart the computer entirely, because running sudo service lightdmn [stop/start] doesn't appear to react).

Turning down the video settings seems to have helped in some cases, but not all of them.

Times it's frozen on me:

• The beginning of The Fallen Start quest part 6 - kill the Wretched Mother, right as you walk out of New Tristram and engage in the monsters on the northern path (repeatedly froze here until I adjusted the graphics down)
• Within the cinematic/event upon finding Deckard Cain
• While fighting the skeletons to protect Deckard Cain
• When about to enter Leoric's passage after Cain sends you back to where you found him

That's as far as I've gotten through the game so far. Additionally, this doesn't happen on other games I play and seems to only occur with Diablo 3.

Has anyone else run into this issue and know a possible cause or fix, or at least know where I can look (and what to look for) to figure out why this is happening?