Hi civilenginerd,
Have you updated your drivers from NVIDIA lately? Their first drivers for Win7 were flaky. Drivers released since last April should be OK, at least in my experience. When tested this morning, no driver crashes occurred under the conditions you stated when using a Win7 x64 system with an NVIDIA 9600 GT and driver version 8.17.11.9745 (April 2010).
If you are using the most recent drivers and are still experiencing driver crashes, you should disable desktop composition for L3DT. You can do this by right-clicking on the desktop link, selecting the 'compatibility' tab, and enabling the 'disable desktop composition' checkbox, as shown below:
Best regards,
Aaron.