Just had it occur again waking from sleep. Thinkpad T410 with NVS 3100M, kernel 2.6.32-21, driver 270.41.06. Didn't boot with intel_iommu=off, but I've had VT-d disabled from the BIOS since my last post. Gonna see if I can possibly revert to 2.6.31, based on BarbuDreadMon's experience.
Edit: Unable to revert since 2.6.31 is incompatible with my wifi card.