It looks like your network has found a new device. If you're not sure what it is, you can go onto Google and search for "UPnP Tools for Developers." You'll want to find a program called "Device Spy." If you install and run that, it should be able to find and identify the devices on your network. Just find the device that matches the Unique Device ID - the 6F3DC09E... and figure out what it is.
Otherwise, you should be able to right-click the device in the "Playing From Main Library" tree and select "hide."
Thanks for your reply.
Both the hide and the rename options are grayed out for this item.
I did run device spy. I have an HDHomeRun cable card tuner. It has three tuners built-in. And device spy found three distinct HDHomeRun devices. They are named HDHomeRun DMS 131E3C28, HDHomeRun DRI 131E3C28 and HDHomeRun RUI 131E3C28. I don't know what the DMS, DRI and RUI all stand for, but it is the DMS one that has the indicated unique id for the nameless entry. Notice in the screen shot there is a proper entry for the same DMS tuner. So the same device is being listed twice, once legitimately and once in error.
Another thing probably worth noting is that I have MC installed on another computer on the same network. It lists the same DMS tuner but it lists it only once. Just as it should be.
I tried deleting ALL dynamic libraries (by right clicking on Playing from Main Library) but that didn't work. Both listings were re-created almost instantly.
I don't know if you can do anything about this bug because you probably won't be able to reproduce it. Still, if there is anything I can do to help, let me know. At some point I will try uninstalling MC and re-installing it to see if the phantom device goes away.