xorg crashing with "Fatal server error: lockup" in xorg.log and "[drm:drm_lock_free] *ERROR* 1 freed heavyweight lock held by 2" in messages

[Jens Stroebel]

Jens Stroebel wrote:
> conditions:
> xorg-git (xserver, libs, drivers, mesa) from 2007-11-22
> drm from linux 2.6.22.14
> kernel linux 2.6.22.14
> 
> intel 965GM on a latitude D830

just a note:

I forgot to mention that this behavior is !not! volutarily reproducable,
unfortunately.
It happens very rarely and has been observed just once (with an
identical setup running at about half a dozen places).