PC showing up in the "Shared" section of the sidebar

An apparent bug in Mac OS X's file sharing sometimes causes odd PC names to show under the "Shared" section of the Finder's sidebar.

Apple Discussions poster Dan Cavaliere writes:

"I have our 3 Macs connected on a LAN (no wi fi) and recently updated them all to OS10.5.6. Suddenly today the 2 managed computers have an additional 'macintosh' computer showing up in the sidebar. We do have our Wii connected to the LAN but I've never seen it before."

There are four potential reasons why this could happen. The first is that the user has a PC on the network with file sharing enabled, and the user has Windows sharing enabled on their computer. In this instance, everything is working as it should; however, the three possibilities where things are not functioning correctly could be the following:

1. The computer is falsely identifying itself OS X comes with support for Windows networking, and sometimes configuration glitches can cause the computer to turn this on and broadcast its name to itself. It is also possible that even though windows networking is disabled, other it may pick up names from other computers and display them in the Finder, even at a later date when the computer is not connected to the network anymore.

2. The computer is picking up a router or printer device on the network Many network devices use file sharing protocols for various services, and its possible one of these is showing up. This may be especially true if the device seems to have random letters and numbers for the name instead of something like "joe's computer".

The computer is getting conflicts with other networking protocols. OS X contains many networking technologies and devices, including infrared, bluetooth, WiFi, Ethernet, FireWire, and uses a variety of protocols to establish connections (bonjour, Appletalk, SMB, etc). It's possible that bluetooth file sharing can cause odd devices to display, and this may also happen if Bonjour is discovering devices it normally shouldn't.

For the most part, when users get information on these "rogue" computers, they're identified as Windows PCs on the network. The fix for this seems to be to toggle Windows networking on and off, which will refresh the networking protocols and allow them to rediscover the networked devices. To do this, go to the "Sharing" system preferences and under "File Sharing" click "Options." Then check the option for "SMB" and click "Done"; repeat this to turn SMB off if desired. The rogue PC device should disappear, though this might require a restart to fully take effect.

Additionally, users have had success in turning off Bluetooth Sharing (also available in the "Sharing" system preferences).

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