Thank you for responding. I am pretty sure, that the power supply is not the problem. The power supply is a raspi 5.1V, 2.5 Ampere power supply. The raspi is running on LAN and the only connection is one external USB harddrive 2.5 ", 500GB for the music data. The raspi is running 24/7 days and in the beginning I found a problem with the router which had only a lease of 1 day. I changed that to a fixed ip address and then the raspi run for about 2 days. I am not sure if there are running some logs under MC23 ? Nevertheless I implemented a crontab for restart every day at 3 am. I am controlling the MC via JRemote with the iPad or EOS with the android tablet. The music is playing in three different zones, but only one zone at the time.
I am not quite sure, but the last time the MC23 run for 3 days (which was record !) and my daughter started her old android tablet with gizmo to control the music. After that the MC crashed again. Can it be that the old gizmo is not any longer compatible with MC23 on raspberry pi?