Assume you've restarted the box and given your remote a power cycle (remove batteries)
Make sure you don't have any other device or receiver close by which might be trying to decode the infra red transmission from the remote.
There are a few posts about that mention similar things.
People are loading previous versions of the firmware by a RS 232 cable as they
can't get into the menu, like yourself, it sounds like a problem with the latest firmware
to me, but I don't have that box anymore so I can't confirm.
See post #134 in the tutorial
You will have to contact your server and get them to Email
you your line details if you haven't got a copy.