Right click on the start button, click on Explore click on your C drive or the drive NWN is loaded in. left click once on the NWN file not the + to the left.
Next look for the square black icon with the nwn eye in it and the word MAIN in
red letters inside the bottom of the Icon and the then under it says nwmain.
Next right click on that and select send to the desk top (create shortcut) and now you have a NWmain exe on your desk top if you want to launch the DM part rename the shortcut. shown below!
Do this once the icon is on your desk top right click on it and click properties. Then in the Target box add this (depending which drive its in C:/D:/E
C:\NeverwinterNights\NWN\nwmain.exe -dmc
The space and -dmc after the .exe opens the DM Client and not the Player Client.
Hope that helps.
you should be able to play now if you were having problems starting the game.
Bioware is aware of this problem and their programers are ALL working on a fix for this and will have a new patch A.S.A.P.