From the same directory I always run it. Originally from my desktop shortcut, then from the actual directory. Nwn Main doesn't work either and just results in a windows error message: "Nwn has stopped working". I run as admin etc.
I couldn't find my CDs so I spent $10 on GOG I later found my CDs as the GOG version was installing lol but hey I have 2 keys now so I also have 2 accounts so save your current .ini files which have your keys so you can get back onto your toons as well if you want you can then also dualbox.
For the actual issue are you running ARF2? It updates your nwnmain.exe file I believe so you might try giving that a shot first.
I ran arf2 and instead of the "I'm not in the..." error message, I get the standard opening window that has the "play", "configure" etc. options but when I hit play windows pops an error message saying, "Nwn has stopped working". Nwn config doesn't let me run it, popping an error message that says, "EA access violation". Did system restore. I always run as admin. Now I am dowloading new video drivers just in case.