7ef6a8d created the issue

OK, I'm connected to an ftp-server with a personal account.
When I move a file (or folder) within the ftp-account (not transfer to/from ftp-server) to another folder, Cyberduck displays an error popup saying:

FTP Error: Cannot rename file 
/myfolder/myfilename 
renamed

In the Cyberduck browser the file (or folder) seems un-moved, but
when I hit the Refresh button, I see that the operation has ... SUCCEDED.
The last line in red ("renamed") hints that the operation was succesful, but why the error notification?

This happens with all files/folders on this server...
Everytime, all the time.
Mac OS X 10.3.9.

Server transcript:

NOOP
200 cool
CWD /private
250 switched to private
RNFR to-do #2.txt
350 proceed with the destination name
RNTO /private/bup_2005/to-do #2.txt
200 renamed