TheGreenButton - Windows Media Center Forums

I had an issue with my extenders not seeing my media libraries that have been setup automatically on Windows 7 PC. The PC could see these libraries but the extender could not see my Music, Photos, Videos, and Movies. Enabling the guest account and giving it read access to the respective folders fixed the issue.

You could also just add the ANONYMOUS USER well known security principle to both the share and file system. More secure than enabling the guest account.