Character formats broken

Dear ZMS-Developers,

I have a problem with the Character formats configuration page.
I tried to introduce a new character format and unfortunately used an
image with an existing id.
Now this configuration page is broken. I only get the frontend with this
error:

Site Error
An error was encountered while publishing this resource. 

Error Type: KeyError
Error Value: 'id'



________________________________________________________________________

Troubleshooting Suggestions

      * This resource may be trying to reference a nonexistent object or
        variable 'id'.
      * The URL may be incorrect.
      * The parameters passed to this resource may be incorrect.
      * A resource that this resource relies on may be encountering an
        error.

For more detailed information about the error, please refer to the error
log. 

If the error persists please contact the site maintainer. Thank you for
your patience. 

error.log tells me this:

2008-08-05T16:04:27 ERROR Zope.SiteErrorLog
http://aaa.aaa.at/AAA_Site/AAA/content/format_manager/manage_charformats
Traceback (innermost last):
  Module ZPublisher.Publish, line 119, in publish
  Module ZPublisher.mapply, line 88, in mapply
  Module ZPublisher.Publish, line 42, in call_object
  Module App.special_dtml, line 65, in __call__
  Module DocumentTemplate.DT_String, line 476, in __call__
  Module DocumentTemplate.DT_In, line 703, in renderwob
  Module DocumentTemplate.DT_Let, line 76, in render
  Module DocumentTemplate.DT_Util, line 196, in eval
   - __traceback_info__: REQUEST
  Module <string>, line 0, in ?
KeyError: 'id'

What can I do to get this running again?

Regards
PeterZ