Mplayer (and others too) occasionally pauses for no apparent reason

[MR ZenWiz]

I run Xubuntu 16.04 and I like to play long, random selection music
play lists using mplayer.

Occasionally the sound just pauses for no apparent reason.

I have checked with top and htop, but there's nothing consuming a
significant piece of CPU time (i7, 8 cores, less than 1% on up to four
CPUs when this happens) or memory (less than 4GB out of 16GB in use).

I though t it might be Chrome, as I routinely have 4-8 tabs open, and
there are as many as 30 or more Chrome related entries showing in
htlop (I can't count them - too fast), but when exit Chrome, it still
happens.

I am running with my home directory encrypted, but the music is not
there, it's in an open directory.

The system monitor applet doesn't show any significant disk usage (I
have 6TB total, plus a 250M SSD drive for the root.

Not sure where to look - suggestions welcome.

Thanks.
MR