Webmin bad file descriptor on Filemanager

[manti111]

As FTP never seemed to work on Debian, I tried webmin with its filemanager. This was not a problem until today. A certain user with access to certain directory can no longer edit, or write to files, it error out with bad file descriptor. Doing exactly the same as root does not give an issue for some reason. I check permissions, settings, but I cannot find anything wrong. Also creating a clone of the user and then trying also seems not to work.
It seems to be related to that specific directory. I tried, with success, editing in another directory using another user.
Webmin is at 1.500, the server runs Debian Lenny.

=== Edit ===

We managed to crack it. It was a group issue. Webmin seemed to expect the group to be the same as the user. A simple chown -Rv foo:foo /dir/ect/ory/* seems to have fixed it, for now.