System Environment:
--------------------------

--Platform:945g

--Architecture(32-bit,64-bit,compatiblity):64bit 

--2D driver:
 e720ae4476c3f986f623ce0f0ab9775b8b9b7e05

--3D driver:
commit ffee86f69711e96c5a9ae68376aaf8a044c73dc8

--DRM:
commit cfa21b22b43c7113107b5eb086b5f4d4ec36dc0a

--Xserver:
commit eab0c4e49015fe96f6d985316f9c5fa28a7eb1fe


--Kernel:
2.6.23


Bug detailed description:
-------------------------
startx ,run glthreads . it run failed and  soon crashs X .
and then I turn off the TTM ,the result is the same as before.


Reproduce steps:
----------------
 run glthreads



Current result:
----------------
fail and crashs X .


Expected result:
----------------
run normally