Radio shuts down and restarts by using a USB Stick

[SwissJaguar]

Hello everybody. I have recently had the problem that if I want to listen to music from my USB stick via the multimedia interface, the radio suddenly shuts down and restarts. I have already tried to re-format the USB flash drive and re-play the music but that did not work either.
Has anyone ever had this problem too or does know a solution?
Thanks in advance.
Greetings from Switzerland
Stefan