When I switched my 4000T on last night the picture on live TV (all channels) was really dull - it looked like the brightness had been turned down. Similarly the EPG was very dull and almost unreadable.
I did a test by recording one of the dull TV programmes. When I pressed HOME to go to recordings the icons was bright as usual. When I played back the recording of the dull broadcast, the recording played back fine.
I powered OFF and ON and the TV picture was now bright and normal and all was OK.
It appears therefore that live TV (all channels) and EPG were being displayed at reduced brightness. However a recording was recorded at correct brightness and was displayed at correct brightness.
At no time did I make any change of the TV brightness or contrast controls. Also I could switch between dull live TV > bright recording of that dull TV > dull live TV > bright recording of that dull live TV.
Strange ...