Created attachment 102449 [details]
I just found this in dmesg:
[ 8916.544423] [drm:ring_stuck] *ERROR* Kicking stuck semaphore on render ring
[ 8916.544428] [drm] GPU crash dump saved to /sys/class/drm/card0/error
[ 8916.544429] [drm] GPU hangs can indicate a bug anywhere in the entire gfx stack, including userspace.
[ 8916.544430] [drm] Please file a _new_ bug report on bugs.freedesktop.org against DRI -> DRM/Intel
[ 8916.544430] [drm] drm/i915 developers can then reassign to the right component if it's not a kernel issue.
[ 8916.544440] [drm] The gpu crash dump is required to analyze gpu hangs, so please always attach it.
I was playing a video at that time.
Linux intrepid 3.14-1-amd64 #1 SMP Debian 3.14.9-1 (2014-06-30) x86_64 GNU/Linux
*** This bug has been marked as a duplicate of bug 54226 ***