Oh, trust me… I have rebooted EVERYTHING - several times - not just rebooting, but unplugging and letting sit for 60 seconds before replugging power. I moved a movie to the SD card and I am going to try watching that tonight to see what that does. I’ll report back after the feature film 
As a technician… I hate intermittent problems. I took your suggestion and put a video on the SD card. It played just fine. But so did the other videos I watched streaming over the network last night! The MP3s still pause and hesitate, though, just not as often. It’s not wonder I’m going bald!
OK… I’ve taken all of the steps that everyone has suggested and the MP3 playback is still hesitating, yet the video - a higher bandwidth requirement - isn’t. This is the latest log if anyone has any suggestion…
You’ve tested well, so I assume that you tried copying some of the offending MP3’s to the SD card also?
Well… no. I copied the video over, but not the mp3. I would think if the network could handle the bandwidth of a video, it ought to be able to handle a measly mp3!
I would think so also. But…
One other thought, have you ssh’ed in and run top while this is happening? Maybe something on the Pi is using up the CPU causing your glitches.
No, but I can do that. I’ll do that tomorrow and report back
So far it has been working, so… I don’t know.