Unstable HDMI signal

[MichaelRu]

Software
XBian version: 1.0
XBMC/Kodi version: 17.1
Overclock settings: Default

Hardware
Device type and model: Raspberry Pi 1, Model B 512 MB
Power supply rating: 1200mA
SD card size and make/type: 8GB
Network (Ethernet or wireless): Ethernet
Connected devices (TV, USB, network storage, ...): None

Log files
Link to logfile(s): http://paste.ubuntu.com/24372971/

Problem description:
I just installed XBian on my Raspberry Pi. When I connect it to the receiver in my home cinema then the beamer switches off every few seconds while I'm in the Kodi UI. A few seconds later, it comes back on. The display of the receiver flickers as if it doesn't recognize the signal from the cable.

When I connect the Pi to a normal monitor (with the same cable), then everything works.

I already added hdmi_safe=1 and config_hdmi_boost=7 to the config, but that didn't change anything. hdmi_safe changed the initial resolution to 480p but as soon as Kodi is started up, it switches to 1080p and has the same problem again. There are no messages in the log file when the signal is lost/comes back.
It seems like those problems only occur, when the Kodi UI is already started. Everything was ok during the installation routine from XBian and I also never see problems while the system boots before Kodi is up and running.

I had Kodi 16.0 (I think with OpenElec, but I'm not sure) on the same Pi connected through the same cables to the same receiver before and that worked. Now I wiped the SD card to install the newest version and the UI is unusable.

I also tried OpenElec 8.0.0 and 7.0.1, LibreElec 8.0.0 and 7.0.0 and OSMC, but they all have the same problem. That sounds like it is a problem between the Pi and the receiver, but it worked with the old version and it still works before Kodi is loaded up.

How to reproduce:
Just boot up and wait. After a maximum of 30secs the screen will get black.