Same problem here:
Occasionally (not reproducible) there is a dropout in playback.
If i try to play the same title from it's beginning, there is no dropout any more.
Only some time later the next dropout appears.
Dropout is not quite the correct term here because it doesn't drop to full silence but only gets more quiet for a fraction of a second.
I had a demonstration of the aria music server (
http://ariamusicserver.com) lately, where i perceived the same kind of dropouts.
The aria server uses JRiver MC as their software, too - i think the Unix version.
This is very annoying.