You could try to delete the last quicksave from its folder, maybe the old file is corrupted and causes problems. Savegames are not necessarily deleted if you de-install the game.
I can't take a look at the save location now, but its is one of these:
C: -> User -> {Username}-> AppData -> Local -> VirtualStore -> Program Files (x86) -> BioWare Corp
Game install Directory
You may have to make invisible files visible to navigate into the first path:
http://windows.microsoft.com/en-US/windows7/Show-hidden-files Also: How much memory do you have installed? NWN has some memory leaks which can cause crashes after a long period of gameplay.
Me research shows that all people who had problems with quicksave, where successful using normal saves to circumvent the problem. May be an option.