Oh dear :( then I guess you have a particular machine that needs a special fix from someone with real technical knowledge. Post in the BSN tech help forum http://social.bioware.com/forum/1/category/187/index , mention everything you did and try to post machine specifications (read the "start here" sticky for what they need. )

Good luck :)

My solution after everything else I tried failed:

ALT-CTRL-DEL and make sure the nwn and nwnmain exes are ended.

Go to your C: drive and in the top right type a3d.dll in the search box.
Attempt to delete every file that comes up. Some won't allow it, but the important file that is causing NWN to crash after splash will delete.

Launch NWN and be happy :)

Deleting this file (its an old sound driver for certain chipsets (even if you don't use that chipset)), is all I needed to do. I didn't have to change the install location, permissions, or run in any compatability mode.