This may sound silly, but...
I just installed NWN from the GOG installation, patched it with the 1.69 Critical Rebuild, entered my own CD keys in nwncdkey.ini.
The game works very well, but there is a weird problem remaining : the Enter/Return key doesn't work at all, neither in solo nor multiplayer game. Therefore I can't chat with other players, unless I click every time in the chat bar, which is VERY annoying.

I tried looking for the keyboard settings, searching on the Internet for a solution, but I'm out of luck with this one. Anyone knows where I could check and modify the keyboard assignment for chat, or make the Enter key work with this game ?

Are you using any other software in conjunction with NWN? ...like Xfire or such...

Another thing I can think of is that you should check that you haven't bound the Enter key in the game to do something else...

The Enter key shouldn't be bound to anything....

I don't have Xfire, I play NWN on a really simple laptop, there is almost anything but Windows and a few softwares that I need.
The Enter key is not bound to anything in the game settings.