Hi, LUCRETIA.
I haven't read much through the above posts so I apologise if I go over past stuff.
From what I remember of the Neverwinter Nights Gold installer, you don't need to install the expansion. There is, however, a "critical restore" on the CD which makes NWN:Gold unplayable because it asks for the Shadows of Unretide disc.
Could you have installed more than you were meant to and caused the problem that way?