---------------
Display Devices
---------------
        Card name: NVIDIA GeForce 7600 GS
     Manufacturer: NVIDIA
        Chip type: GeForce 7600 GS
         DAC type: Integrated RAMDAC
       Device Key: Enum\PCI\VEN_10DE&DEV_02E1&SUBSYS_21C319F1&REV_A2
   Display Memory: 512.0 MB
     Current Mode: 1600 x 1200 (32 bit) (60Hz)
          Monitor: Plug and Play Monitor
  Monitor Max Res: 1600,1200
I've since taken the resolution to 1024x768 and reset the refresh rate to 75.  We turned off the detailed terrain and the bump texture and it doesn't lock up any more.  But...form follows function.
Anybody else?