Is that S1 or S2 version? Did you get the update today? 

I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your Sonos system and network.

Hi Bruce,

Enlisted the outfit that installed the system and did as you described.  (It is a S1, and no I haven’t installed the update (yet).)

After power cycling all the amps and the router, clearing the queues of all the amps, and making sure I was not logged into Spotify (independent of Sonos), the problem went away.

Would be nice if there some general guidelines regarding song queues, number of different Spotify streams possible, etc.

Thanks for your timely response.

Bernard