Just in case a quick fix which worked for me might also work for someone else with the same problem, here is part of a bug report I submitted to Humax support on 01/05/2014:
Dear Sir,
My HDR-2000T experiences HDMI related problems similar to those widely reported by other HDR-2000T users on Humax forums.
HDMI problem #1
---------------------
I have compared my 3 Humax machines and the following table diagnoses unambiguously that the HDR-2000T displays anomalous HDMI behaviour. The HDR-2000T frequently fails to initialise the HDMI audio signal properly when turned on from standby and as a result, the TV does not recognise the audio signal (see *No references below). Tests were repeated for each of the 3 machines using the same HDMI socket and lead connected to a Panasonic Viera TX-32LXD70 television. Both HDMI sockets of the Panasonic Viera TX-32LXD70 television were tested with similar results.
+----------------+-------------------+---------+--------+--------+
| Humax model | Firmware | Loader | Video* | Audio* |
+----------------+-------------------+---------+--------+--------+
| HD-Fox T2 | KZTFT 1.02.29 | L7.27 | Yes | Yes |
| HDR-Fox T2 | FHTCP 1.03.12 | a7.31 | Yes | Yes |
| HDR-2000T | UKTFAC 1.00.07 | 1.02 | Yes | No* |
+----------------+-------------------+--------+---------+--------+
*Video/*Audio = Yes/No: Indicates whether the relevant signal is recognised following switching on from standby
*No: Audio however can be restored using the TV controller by first re-selecting "TV" and then the HDR-2000T HDMI socket.
Humax's response was:
Thank you for contacting Humax Support.
The first two issues could be related to HDMI CEC options on the TV and this would need to be disabled if they are enabled. On Panasonic TV the feature is called VIERA Link, HDAVI Control or EZ-Sync.
The RF Loop through on the HDR 2000T is enabled when switched on and this was the orignal specification on the box. We have taken on customer feedback and we will be introducing RF Loop Through in standby via a software update in the near future.
My comment: The Humax advice about the HDMI audio problem proved to be a red herring since the VIERA Link option was already disabled.