Thanks for your quick reply.

His network is a LAN shared by a whole apartment complex, and it is not accesible for browsing, f.ex. via "network neighbourhood" It's just because they are all connected through some kind of "big" internet connection, common for the whole complex.

The files were the files he shared in limewire, and I'm trying to encourage him to keep sharing his media files + the one's he's downloaded.
The real problem is, if it's not some mistake his neighbour made, that the files were accesible all over the LAN, without other limewire users looking for the specific files. I mean, he dosn't mind sharing stuff, but he certainly doesn't like all his neighbours knowing that "the guy from 2B likes this music, these movies" and other stuff.

I've told him to move his media from the folders commonly shared by windows, but somwhow I don't think that's it.
From what I heard from his recounting, his neighbour somehow got all the music he shared, with clear indication, what username it came from.
As you point out, I was thinking maybe it was something like itunes, that automatically makes shared music visible on a LAN.
Again, if limewire shares stuff automatically, and in a very visible way, on a LAN. Is there some way to turn this feature off?