Running Win 7, just installed the Critical Rebuild Patch and I'm getting this weird graphical error where the screen will flash constantly. Graphics and DirectX are both updated. Not sure what to do. Any help?

Do you have a multicore processor? If so, go into your nwplayer.ini file and change the Client CPU Affinity setting under [Game Options] to force the game to only use a single processor. Possible values:

-2 - Turns off CPU Affinity
-1 - Defaults to 0...
0 - Use Processor 1
1 - Use Processor 2
2 - Use Processor 3
...etc

Sorry where do I find the nwplayer.ini?

In your NWN install directory (the same location the game's executable can be found in)

Looks like its already set to: Client CPU Affinity=0
I should mention that I apparently have an Intel Core 2 Duo

What graphics card are you using? Flicking graphics may be an indicator of poor OpenGL support; occasionally rolling back to an older driver rather than using the most recent version can correct this.

Well don't laugh... it's pretty terrible.

ATI Mobility Radeon X1400. I think it runs some weird Dell custom drivers too.

Have you tried all the possible graphics settings you can think of? There are some weird issues where maxing out anti-aliasing will fix some problems, for example. Other than that, I would tweak settings through your graphics out of game (several things such as forcing the game to utilize or not utilize certain graphics features are available through here).

I run a similar generation card (X800 XL) that manages to run the game fine, so in theory it should be possible.

Perhaps check your sound drivers are up to date. Some video problems are caused by sound issues, strange as that may seem.

Good Luck :)

You tried everything on this list?

http://www.gog.com/en/forum/neverwinter_nights_diamond/game_will_not_run/post27