Hi pauldst, and welcome!
Is the game crashing when you are conquering a city or are you using slaves when you conquer a city?
If yes, it could be the
diplomod 3.6 bug. If you have a save of the turn when CtP2 crashes, load it and then Reloadslic to reset some settings.
Hit the
' key
Type
/reloadslic in the text box
Press
Enter to validate and
Enter again to close the window
As a rule I am doing a quicksave (only takes a couple of seconds) every turn before ending it or after I have done important and long things so that I can reload the game if there is a crash and thus have the possibility to
Reloadslic.
See also
this thread for other tips.