I also have a Denon CEOL with DLNA/UPnP playback capability. I use MediaMonkey to play a list of around 20000 mp3 songs that are on an HDD connected to the Denon CEOL. Frequently, the MediaMonkey player freezes. I've observed this problem in two different situations:
1. Sometimes the screen goes blank, and you can't close it except through the Windows task manager. This happens very often when I play the HDD connected to the Denon CEOL and the connection to the Denon CEOL for music playback is via Bluetooth.
2. The second failure is more sporadic, and happens when I play the HDD connected to the Denon CEOL and the connection to the Denon CEOL for music playback is by DLNA/UPnP. The music doesn't stop, and this message appears:
When I press continue, this other message appears, and finally the music stops.
This second failure can take days to happen again.