Jim, maybe the term should be re-start. I will be listening to music and all of a sudden the JRiver stops playing. Then I have to go to the JRiver software, close it out and open it again. It doesn't happen all the time, but I believe it should never happen?
That should not happen, but that is quite different than (what we both thought you meant) requiring a restart of the computer.
I still don't know, at all, what this means:
hooked up to a Electrocompienent streaming integrated.
No idea what that thing is, or how it is hooked up, or anything like that. If it is, indeed a problem they can reproduce with MC, I'm sure they'll work to correct it, but we'll need to know quite a bit more details about what you're doing (or using) that could be causing this... As I mentioned above, I have a Mini and have no such problems. If I'm not mistaken, it is developed (at least in-part) on a Mini. It isn't likely to be some sort of MC > Mac Mini conflict. It is something more specific to your setup with the Mini.
So...
1. Let's start with that crazy Electrowhatsiehoosie thingy you mentioned. What the heck is that thing?
2. How do your speakers connect to your Mini? Is it through that thing? Is that thing a DAC connected to the Mini directly, or a DLNA receiver of some kind over the network, or something else entirely?
3. What special settings are you using in MC, if anything non-default?
4. If it is a network device, we'd need to know a bit more about your network setup, and what you've done to ensure you aren't just seeing common networking issues like WiFi interference or routing issues (maybe a flaky gateway).
I'd love to be able to help you, but there isn't enough actionable information in this thread to even start making guesses.