I gave up on Nokia Music, I now just use Pandora on wifi or on LTE. Nokia music was great than my Lumia 920 started to stop the music in the background ever so often. I have found that playing music on Pandora a much better experience.
Seems it is related to audio. There is a game that I was playing with no issues before firmware updating. But now the phone restarts from time to time when I was playing the same game. If I disable the audio, the phone won't restart.
Well, experienced rebooting even with audio off. Then I noticed the phone was really hot. I believe it is because of the free case we got from HSN. I removed the case and played the same game for awhile. No rebooting.
Mine is rebooting while listening to music, but I don't have a case on my phone. Not to say that your cases couldn't also be causing something to go wrong
Yes, I to experience random reboots when listening to Nokia Music offline mixes. It is the app Nokia produced. Not the firmware, battery or case. It is the only time it happens, could also be related to the OS, it is Windows afterall.