Hello, I've had the same problem here on etch amd64.As mentionned just above, FileZilla runs fine after closing the error message. But this is still annoying for our users. As a quick and dirty workaround I've added this line to /etc/environment to get rid of the error:
FZ_FZSFTP=/usr/bin/fzsftp -- _gilles. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]