Here's another idea. Try a clean boot. These instructions tell how to do it in Windows XP, so it might work differently in Windows 7. Find msconfig.exe and make a shortcut on your desktop. In my Win XP computer, it is in C:\\WINDOWS\\PCHEALTH\\HELPCTR\\Binaries. Run it, choose Selective Startup, and uncheck everything except System Services. Next, go to the Services tab, check Hide All Microsoft Services, and then click Disable All. Click OK and let it reboot the computer. After playing NWN, to go back to normal, run msconfig again, choose Normal Startup, click OK, and let it reboot.
It will be a hassle to have to do that every time you play NWN, but if it works, it's better than not getting to play such a great game at all.