We've got a Windows 7 PC with a Windows Media Player music library that includes both files on the internal hard drive and files on a USB-attached hard drive. When we browse this library from another Windows Media Player (on another Windows 7 machine) we see only the files residing on the library host's internal drive. The files residing on the attached drive don't show up at all, yet on the host they appear undistinguished within the library.

Is there a configuration change we can make to cause the attached files to be shared properly?

We've turned on read-sharing for "Everyone" on the USB drive, but that hasn't helped. Also it might be worth noting that this issue behaves the same way for us if the client machine is a Playstation 3.