Just tried to play NWN1 via GOG Galaxy and it crashed at startup, not even any logos showed up. Good thing I didn't have to change back the resolution from what was apparently 640x480.

My system is the following:

Windows 7 x64
Intel Core2 Quad Q9450
8gb RAM
GeForce GTX 660

Run as admin in compatibility mode.

Try changing Client CPU Affinity=0 in the nwnplayer.ini to another value like -2 or -1.

The Nvidia card may prefer you to turn threaded optimization off for nwnmain.exe in your card's control panel.

Make sure to apply the Critical Rebuild that corrects some graphics issues of the newer cards/driver encountered after the standard v1.69 patch was released.

Actually, kinda solved it.

The problem was that it crashed BECAUSE it tried to run as admin. When I've made it run as invoker (via removing resource 24/1/1033 via ResHack, a.k.a. manifest from nwmain.exe that forces, then removing "run as admin" from compatibility settings, but making it so it runs in compatibility with WinXP SP3, then making installation directory readable and writable to all users - last of which may not be necessary) it suddenly started to work properly.

TL;DR: It crashes BECAUSE it tries to run as admin, when bypassing UAC prompt and run as invoker, it runs fine.