I have 2 PS3s. One is an older "Fat" 60GB model, and the other is a 160GB slim model.
I'm having 2 issues. One is whenever my computer locks after inactivity, I can no longer access the media server on either ps3. This is resolved by restarting the media server from within the Main Panel.
After that I can access the media servers on both PS3s. But the second issue arises with the old fat model. On this ps3 when navigating through all the folders I always see "There are no titles." On the slim ps3 all content shows up and plays fine.