Having looked a bit more into this problem I need the following information;
where does LinuxMCE call mediatomb to start (ie where are MCE's start up scripts?).
I have checked the mediatomb config file and although logins are listed within the file (mediatomb, mediatomb) they dont work. Even if you edit the config file and set logins as active then the username and password from the file do not work. The mediatomb website says that the username password issue is related to not connecting to the correct port for the upnp server or another issue in the way mediatomb is called to start up.