When playing NWN, I have had some serious stability problems while playing using my XP platforms. This article was written in Nov 2008 and is probably pretty redundant.
This thread at Planet Neverwinter Nights Technical Support Forum recommends turning off the shiny water effect and applying a hak pack.
I have done the first, but not the second. In order to apply a HakPak, I need to know how. 🙂
This article is really not so useful without more dates and version numbers, but it did apply to Windows XP as a platform. As it says above, the article is probably redundant.