Can not upload picture through WYSIWYG

[tschodro]

If a user would like to upload a picture in the editor, a new window pops up saying :Your session has timed out. This usually happens if you've been away from your browser for a long period. Login again using the fields below.
And this is the link www.mysite.de/admin/de/class.devedit.php?rnd372ToDo=MediaManager&obj=image&loggedout=true
But the user should have nothing to do with the admin. So I tried to log in as admin and to upload as an normal user again, than it dit work. Logged out as admin, same problem as before.
Someone has an idee how to fix this, would be realy important for me!!

Edit: The link is not working since I replaced my site name through mysite!!

[tschodro]

Done!!! For those who had the same problem, it was a bug and got fixed!! Thanks for the good support.

[bambipower]

how to fix it?

[tschodro]

This is the mail I got:
"Hi Thomas,

I've reuploaded the files but found the problem is due to bug in the current release. I've patched this bug on your website and in our development version. The patch will be included in all future releases."

Hope it helps you out.