Actuallyyyy, there are some specific settings to adjust in your nvida graphic card control panel, for nwn specifically, that will help lots. ( I use Windows 7 too and had some performance issues)
I'm sorry I haven't memorized all of them, it's been literally over a year since I tinkered with it.
Threaded optimization needs to be off...that one I remember. It stops unsupported multicore tech.
Also increasing a setting that allows additional ram to be used was modified via a txt (ini?) file in the game folder.
In the past there have been issues in game when the setting 'environment mapping on creatures' is on, try turning it off.
I hope other people know off the top of their head the nvida stuff and post the specifics.
...if not, tinker with the settings, see if it changes. Be sure to restart nwn to make extra sure the various changes are in effect. If something has no noticeable effect, set it back to default to avoid causing any issues.
-and yes, run admin mode in a compatible windows mode. Like 98.
None of the above 'sounds' like it is directly causing your issue, it sounds like a hak issue indeed - but this other stuff is useful!