I get several crash every day. Right now I'm using the kernel 3.17 with mesa git from ~lcarlier repository (arch linux + kde4) on my radeon hd7970. Switching to stable kernel and mesa don't change the situation. I don't know if this is the same error but I leave my dmesg log from latest crash. The system stop responding and the monitor output garbage. Sometime I can switch to TTY to reboot. Most of time I can't. http://pastebin.com/nkKNQE1f