New "shared" iTunes library

Factual Questions
1

I just noticed that in the side panel of iTunes, under “Shared,” is "Joe Blow’s Library (the name has been changed to protect “Joe Blow”). I’m just seeing this for the first time.

First of all, I’m the only person who ever uses this computer, and there hasn’t been any “sharing” going on. Second, I don’t know anyone by that name. When I try to open the library, the top window says “Loading Joe Blow’s Library…” but nothing is loading. I also get a message of: “The shared library “Joe Blow’s Library” is not accessible for an unknown reason. (-3259)”

What’s going on here, and why can’t I delete it? I can prevent it from showing through Preferences, but I want to totally delete it.

2

Someone on your network is sharing their iTunes library. I’ve seen this happen on Cox cable before. Ignore it, or turn it off in Preferences.

3

I’m not in a network, and don’t know anyone by that name. How did it get there?

4

Do you use a wireless router?
Is it secure?

5

You’re on the Internet, right? Then you are part of a network.
iTunes actively looks for other computers sharing their music libraries. Most of the time this is blocked on a wide-area network, but I’ve seen this sort of thing happen before.