You characters are probably levelling up at that point, which a few people have had problems with if multiple party members level at the same time, or (more rarely) if someone levels while there are still some unallocated points from the previous level up (if there is an indicator on the portrait for stat and ability points, for example, removing either could avoid the crash).
Try getting one character killed before they level, and see if that avoids the crash.
Video Crashing on Level Up -- NPC issue w/Fix (the possible fix is dismissing a companions, which is not applicable in this case)
Please email supportdos@larian.com, with a description of the problem and the report.zip file generated by the
D:OS support tool (for the PC version). The report will contain system and game information, any crash dumps, and your saved games. To reduce file size, if that is an issue, you can delete all but your save before the orc fight.
While this is a know issue, it is not reproducible, so additional information may help isolate the cause.
