Ethernet cables spontaneously failing is not a very common problem. I'm starting to suspect there is something a bit flaky about the Ethernet port on the Mini. While dealing with my Mini problems, I've noticed that just brushing against the Ethernet cable can make it lose link. My usual problem is I pull the power cord from the back and reconnect it (which I've probably done more than anyone on the planet aside from Tivo employees) and when it reboots it has no link, so I wiggle it around a bit or maybe unplug/plug and it works. At first I thought it was the cable, or that it was only one of my Minis, but it's definitely happened with 3 different cables (which I believe are of differing providence), and using 3 different switches, and I think it's now happened on all 4 of my Minis. That is unusual for ethernet connections in my experience - if you don't insert the cable fully that's one thing, but once it "clicks" into place it's usually a very solid connection and even pulling on the cord won't disrupt it.