I also have this problem.
surely there must be a common link?

im playing using the incomplete/buggy (i think?) templates (lich, demilich, half-celestial, etc) and also have CEP with the CEP/PRC merger installed. not sure if any of these things are factors.

i will try to run it in various compatability modes and see what happens

EDIT: both XP, and 98 crashed at about 20-40 minutes
save game still had barbarian portraits

EDIT: alright i think i fixed it, 2 hours no crash

1. reinstalled from scratch
2. patched to 1.69
3. applied PRC, then PRC_OCfix to the OC's
4. made sure to use the NWNX_funcs thing when using templates (eg celestial)
5. did not install CEP