You can enable Dolby Digital again by browsing to a hidden location using your PC
Switch the showcenter on
Unsing
an internet browser on your PC type
http://192.168.xxx.xxx:2020/set_amx=ON (replace the xxx with your IP
address with your own showcenter IP address)
If this works correctly then you should see a message "amx : ON" in your browser.
Go
to the showcenter and press the B (green) buttton, and you should see a
new option "Dolby Digital", where you can select Analog (stereo) or
Digital (5.1) outputs.
Remember to save the selection.
Note that if you select Digital output, then you will get nothing out of the analog outputs, for Dolby Digital sources.
Good Luck
Trevor