You shouldn't need a device driver. You access it as you would any other device that connects through a USB port such as a thumb drive, digital camera, etc.
Reboot your NOOK (hold the power button down for 20 seconds to shut it all the way down, then turn it back on), reboot your computer, then try again.
E-mailing B&N Customer Service is not going to get the job done. The e-mail system is a low-priority service for FAQ-type questions. If you're having a problem, call them at 1-800-THE-BOOK (1-800-843-2665), option 2 for Digital Support.
1. Reboot PC, and reboot NOOK (power down, then back up).
2. When both are finished booting, plug in NOOK.
You can also try plugging the NOOK into different USB ports. Specifically, sometimes the ports in the back are better than the ones in the front because they are “powered.” Also, you can see if the users are connecting via a USB hub and if so, take the USB hub out of the equation.