Well I don't know what it was but I tried it a few days ago and it works just fine, maybe it was the denoising.
Thank you for your help.

There is no error message and blender does hang for a while but it does not crash.
I'm looking at the files in blender "File>Append>Object".
It works in blenders internal rendering engine/Blender Render but not in cycles.
I'm using CPU.

Do you know what the problem could be on my computer and how to fix it?