I play this game since 2002, but I've never come across this problem, and I couldn't find this on any forum.
I try to play the last mission of the Rise of the Elves campaign.
I click on the "end turn", it makes an autosave and the computer starts thinking...
thinking...
thinking...
and thinking...

and nothing happens.
Normally this needs only few seconds, but this time, nothing happens.
I waited more minutes, I went to take a shower. Came back, and the same screen was.

I never experienced in the last 20 years.

What is this???
Any other experienced the same problem?