Since a few weeks my sound is disappearing. After switching off my player for 10 seconds I was able to get my sound back, sometimes after several resets.
Now I have to switch it off during the whole night, to get it working again in the morning.

No hardware or software changes preceeding the sound loss. It makes no difference what kind of file type is played.
I loaded the latest update v7.4.4 r7317 (Europe). The GUI was better then the old one, but my sound is still AWOL at times.
The machine is connected through hdmi. I checked the hdmi port with another device and that channel is ok. The volume on both TV and player are on and open.
I checked for heat building up but the container is completely cool.
Any suggestions?

Hi, please try to use another HDMI cable if can, also check the player audio output is set to LPCM. Then best file you can use to test this issue is by playing MP3, just to eliminate the audio format support/compatibility problem. If the sound goes out again please connect and use the player composite output. If composite does produced sound, then the unit might have inconsistent HDMI port issue which we can consider faulty. If via composite the sound is still not coming out, then we can consider that your player processor is causing the problem.

Roger,

Thanks for the suggestions. I checked all that. The settings don't change and the hdmi cable won't stop functioning without good reason.
The unreasonable thing is that the sound disappearance occurs irregularly and it is difficult to reproduce!

Example: I am watching a movie. Swith off the machine. Switch it on 2 hours later (nobody else is using it) and the sound is gone or not ...

No what? I can ask for an rma to get it fixed, but I am afraid that, when they swith on the machine and it works at that time, they will decide it is working, an send it back at my expence. See my point?

Sorry to hear that, but that is the only option you have if you're device is giving sound issues. So far i cannot duplicate it on my part. If you can try to flash the firmware one more time, please do. Or atleast try a different version and monitor again.