I'm trying to play with Steam for two days, but I've only been able to play the flash-based games. The rest of the time I always end up in a total system freeze. For example, I start "Amnesia". First I have a black screen on my middle monitor. After a while, if I'm lucky, I have the menu of the game. But if I move the mouse, it hangs.
I'm running Ubuntu 12.10 with a 3 screens setup (xinerama), on 2 Nvidia-based GPUs.