FWIW, the Intel 8xx chips have hardware issues (related to broken cache-coherency between GPU and CPU [0]). Older versions of the driver never tried to do any memory management, so were not impacted by the hardware problems.
I have an 855-based laptop as well, and the lockups are very frustrating. But it isn't a matter of "driver bugs" so much as "failure to find a good workaround for hardware bugs".