I had persistent Homesharing problems recently. I rebooted, updated, logged out, logged back in, unshared, reshared, restored. Nothing worked. Simultaneous reboots of all devices involved solved it. In my case - Apple TV 2, iMac, & Time Capsule. Note that I had tried rebooting each separately via power down but without result. What worked was when I did a full unplug of both Apple TV2, and the Time capsule, with a regular power down of the iMac. Don't forget to wait 45 seconds or so. I don't know which link in the chain it was (but I am giving the evil eye to the time capsule right now). I searched this forum and didn't find this recommendation (maybe my oversight), so I thought I would share the tip.