Ok, thanks for the explanation! If time, one could write a short javascript check asuring that no unallowed image name character ist used.

won't help - because you can't depend on clientside validation, you have to do that on the serverside - and if you have to do it on the severside, there is no reason to implement it twice.

Hmm, ok, I understand. But you need at least a error message while trying to upload, that you did choose a unallowed image name. Serverside. Now you still can upload images with this char, but it's invisible when you insert the image-macro in a story.

I believe the problem is namespace related, as you see above the URL with elizabeth hurley works fine in the image-namespace I think the code/parser of the story has a problem with the leading underscore inside the image-name within the image tag, there is no error or exception.