have you made sure that the ip_conntrack_ftp module is loaded as well , #> lsmod If so the only thing i can suggest is disableing DROP on your output for a while and remove the output rules. (set its CHAIN to default of ACCEPT) did this stop the messages ? other than that im not sure . ive tried to follow the entire Kernel Source .c kode, and to me it looks like you may have a problem in your output and maybe contrack_ftp problems ... cya...
