@Dico:

I already removed all actions, but that didn't help. Also all actions write log messages at start, but there's nothing in the logfile. The engine crashes right after the level_load once it reaches the wait(1). If the bug were in the action scripts I guess the crash would appear every time and not just when the level is loaded from a specific one.

@3run:

Yes, I searched a lot on the forum, but none of the things I found helped. My first thought was a broken sprite or model, but I didn't find one yet.

But I'll do some more research on the forum.