John,
That part you found on Amazon appears to be the same one I found on NewEgg, only Amazon seems to have it in stock in the US, so shipping time is a fraction of what NewEgg is quoting. Good find!
As for whether our varying symptoms all have the same root cause, I’m guessing they probably do. I suspect that the TCP/IP traffic that kills the software based stack is somehow causing code or data corruption (I.e. a buffer overrun) which in turn leads to unpredictable execution of the main controller code. I’ve seen a somewhat wide variety of symptoms myself, from simple lockups that don’t seem to have other consequences, to 2 zones running simultaneously even though I have all of my zones set to Sequential mode. Based on these differing symptoms, I will be surprised if the root cause doesn’t turn out to be a buffer overflow (or similar coding error). It’s probably buried in the library that Ray is using.