I'm not sure if mentioning this helps, but I think I'm experiencing the same problem. My system will occasionally freeze completely (numlock and SysRq key don't work) with the image on the screen completely frozen (I don't get any artifacts). I then use the power button to reboot. I use Arch Linux. libdrm 2.4.27 works. 2.4.28 - 2.4.29 freezes. Freezes occur with catalyst-11.11 and 11.12 and with xorg-server-1.10 and 1.11 and with linux-3.1.5 and 3.1.4. $ uname -a Linux J 3.1.5-1-ARCH #1 SMP PREEMPT Sat Dec 10 14:43:09 CET 2011 x86_64 Intel(R) Core(TM) i7 CPU Q 720 @ 1.60GHz GenuineIntel GNU/Linux ATI Mobility Radeon HD 5850 with catalyst driver (I need GPU opencl atm) laptop model: http://www.newegg.com/Product/Product.aspx?Item=N82E16834157515
