It is very likely that the problem lies in the internal properties – the presence of mods, maps, etc., in the game directories. I have completed the map many times, and quite recently, I played the latest version 1.1. The weeks of creatures were announced many times, but no slowdowns occurred. Again, the statistics – already five people have completed this part and have not noticed anything similar. Indirectly confirming my assumptions is the save file size – it is not that large.
This is a special trainer for those who want to “level up” – you get more experience than from a tree, two or three levels. And if you do it one more time, the hero will already be at level six.:)
The problem is that I don't have any other mods for this version of the game – and it can't be the same bug on four different computers – I tried it on my laptop, home computer, daughter's laptop, and even tried to copy the archive to work, where I specifically installed "Heroes" for this purpose.
P.S. At what difficulty level did you complete it? The fact is that, for example, the latest version of the "Grand Frontier" map can be played on "Veteran", but it crashes after the first turn on "Hero".
Added after 30 minutes
I uploaded your save. If you don't move the heroes, the next week – the week of sickness – starts without crashes.
If it's not difficult, please make a save after the computer's turn and the start of the new week and upload it to a file-sharing service – I will download it and try to play further.
