Are you following the destructions for DreamUP fully, m8? Once it's finished the flash, click Disconnect, then Exit.
Power OFF the DM and remove the null-modem cable, then reconnect the scart and ethernet (if using), then power ON again at the mains. I've used it half a dozen times this week- good as gold. And I don't even get a Sat feed installed for another 3 days, LOL!
Cheers- AL