Something happened in the updates after march 28th.
I have made a backup on march 28. A few days later I noticed that my box was active (displaying last channel on panel).
And after a while I noticed that the box went active after 10 minutes.
Here an extract from /var/log/messages:
Apr 7 11:04:06 dm8000 user.warn kernel: set input to 1
Apr 7 11:04:06 dm8000 user.warn kernel: set fb to 2(2)
Apr 7 11:04:06 dm8000 user.warn kernel: set sb to 3(0)
Apr 7 11:04:06 dm8000 user.info kernel: Write AVS: 40 41 00 00 00 00 0a 72 00 06 00 00 00 ff
Apr 7 11:04:12 dm8000 user.info kernel: bcm4501: channel 0 is sleeping now
Apr 7 11:04:20 dm8000 user.warn kernel: HDMI: now powered down
Apr 7 11:14:24 dm8000 user.warn kernel: VIDEO0: dst_left, dst_top, dst_width and dst_height is 0.. reset to defaults!
Apr 7 11:14:24 dm8000 user.warn kernel: set current avs auto aspect to 16:9
Apr 7 11:14:24 dm8000 user.warn kernel: disable wss on display 0
Apr 7 11:14:24 dm8000 user.warn kernel: set wss 7 on display 1
As you can see: box in standby at 11:04 and active again at 11:14.
I use OpenPli4 (same effect with SatDreamGr).
PS: I have a backup from April 3rd, were the problem exists. So it was introduced between 28/03 and 03/04.