[Muleke_Trairao]

The first thing you should try is disabling steam community in-game. To do that:
1 - Right-click on the Fortress Forever shortcut on your library
2 - Click on Properties
3 - Now untick "Enable the Steam overlay while in-game"
4 - Start the game

If that didn't work, you can enable the steam overlay for the game again, because that wasn't causing the crash.

Now try this:

1 - At the top left corner of your Steam window, click on "Steam", then on "Settings".
2 - Click on the "Interface" tab and change your language to English.
3 - Restart Steam and launch the game.

If your language setting was already set to English and you tried the first fix and didn't work...I'm sorry, man, at least i tried. Hope this helps many of you.