[WingsOfStardust]

Done some more investigating, some are suggesting it's the video drivers. Try going back to an older version of the drivers? Just to see if it'll work. *
Source: social.bioware.com/forum/1/topic/187/index/8838761

edit:
"Yeah, ntdll is a pretty common file, Google probably won't find anything specific. Aside from driver updates, the only thing I can think off is a reformat, which is kind of a last resort. My NWN used to lock up after an hour or two of play (no errors or anything), and that ended up being because of my ATI video card."

Source: fop1.forumopolis.org/archive/index.php/t-9219.html

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Well, I'm sorry I can't help more today. I'm going to sleep now after this very long day.
With my leave, may this somehow aid you in your search of the interwebs.