Ok, I'm procrastinating at the moment.
The only thing I can think of is to follow the advice given on the forum at nwn.bioware.com. It goes something like this:
1: set nwmain.exe to "XP SP2 compatibility mode"
2: set nwmain.exe to "run as administrator"
3: run nwmain.exe
You've probably tried the above already, but if not, it's worth a shot, If you still can't connect, then do the same to nwserver.exe and try to host a local game and connect to it.