Persistent crash at around turn 70

[Shadowwalker]

For some reason I start getting crashes in my Hayastan campaign at ~turn 70.
Specifics:
- Win 8.1
- Medieval II Gold, retail version (still doing that "boycot Steam" thing ^^)
- installation is in S:/Medieval II
- usage of that certain third party tool that addresses some RAM problems
- crash happens during AI turn at the turn start of either the Koinon Hellenon or Seleukids
- there's no battles involved and no changes to settlement ownerships

I usually save every 10 turns. First time the crash happened at turn 73, I reloaded the quicksave, which crashed right again.
I went back to the last regular save (turn 70), which crashed at the next AI turn (which ran fine before).
Then I went back to the save at turn 60 which ran fine to turn 70 then crashed.

The detailed log can be found here: http://filehorst.de/d/cIbhuqih . (The mentioned files ("lighting xxx") I haven't touched/altered at all, just saying.)


Edit: Could it be that Java is interferring with the game? (I do not have any technical knowledge so please accept my apology if that is a dumb question...).
I wanted to use the Recruitment Viewer and updated from Java 7 to Java 9 yesterday evening.

Edit 2: Going back to Java 7 and rebooting doesn't seem to help ...