As most of you probably know, there are a lot of people that are plagued by frequent crashes in battle when one or more of the following units are present in an army: Ents, Spiders, Wolves. Perhaps there are a few more as I have not played every TATW based mod, but these three units are the ones most people will encounter.
Edit: Balrogs, Mumakil and Sauron units may crash too, especially when there are a lot of them present. Because these units are usually few in numbers, it seems battle crashes happen not that much when they are present in a battle.
Various people have attempted to solve this annoying problem, but as far as I know nobody has succeeded. I would love to be wrong about this, so if there is somebody out there who does have a solid solution please don't hesitate to share it with us.
What makes it so difficult to solve this problem is the way it manifests itself. As I already stated, some people are having crashes, others (probably the majority of players) never encounter problems with Ents, Spiders or Wolves.
And that is not the only factor that complicates the search for what causes this. The players that experience crashes, usually don't always have them. Sometimes the battle crashes, sometimes not. Sometimes it's possible to play several battles without a crash and sometimes it just keeps crashing one time after another. Crashes can occur right at the beginning, or even before the battle screen has appeared, or during the battle itself. Finally sometimes the game can be closed after crashing by clicking OK in a windows error popup message and sometimes it's necessary to use the task manager to kill the Kingdom.exe process. It looks like it is a totally random thing, but maybe we just are unable to detect a pattern. This is were you (the players) can help.
Edit 2016-08-18: As alreadyded so "charmingly" put it in this POST, it seems there is not much reason left for providing more of the same info already present in this thread. However, anybody who wants to discuss the problem and/or provide possible solutions is more than welcome to use this thread to post about it.
Spoiler Alert, click show to read:
Update March 27th 2016:
Many reports have been submitted to this thread, but sadly it has not yet provided any real clue as to what exactly is causing these crashes. Please keep those reports coming though. Even if they may not help, at least they show the seriousness of this problem.
There is however a little good news to report in the form of a (crude) workaround to the problem, as posted by Ajpav
How to manually remove a unit from the game
Update April 7th 2016:
alreadyded suggested that posting trace logs from when a crash has happened can help in determining what is causing this problem. So if you have such a log available, please include or add them to your post (use spoiler tags!). You can post the whole log, but the last to 100 lines should be sufficient. If you don't know how to enable trace in your logs, have a look at this LINK that shows you exactly what to do. You can use the "Additional info:" to post your logs.2016-08-18: As alreadyded has stated he will not check this thread anymore, there is no reason to post logs, although you still may do so if you think it's useful of course.
Logs can be found in the logs folder: ****\SEGA\Medieval II Total War\logs (this is the location in the non Steam version)