I have been chasing a similar issue for HP Z800 workstations with little to mixed results. To the extent it is relevent, the HP Performance Advisor indicates n/vidia driver 306.68 has been certified for Win7/64, FX4800 and Creo2 as sp60338.exe. (see attached screenshot) Just prior to encountering this today I had installed their latest driver, 311.35 but I do not have much feedback yet.
HP link is: http://isvpatch.external.hp.com/HPPTF2/drvlib/nvidia/sp60338.exe
Dell link is: http://www.dell.com/support/drivers/us/en/19/DriverDetails?driverId=95K0T