Notes about the NWN file extension:
Incorrect file associations could be the result of underlying issues within your PC system. As such it is highly recommended to scan your PC for invalid registry entries, unused processes and other unfavourable system settings to identify slowdown issues.
The NWN file type is primarily associated with 'BioWare Aurora Engine' by BioWare Corp.. Every NWN module (.MOD or .NWM) or savegame (.SAV) is an Encapsulated Resource File (ERF). The ERF format is one of BioWare's methods of packing multiple files into a single file so that they may be treated as a single unit.