it is a long time I have this problem.
This is my configuration:
1 pc windows seven
1 pc windows xp
I have wired network connection and all devices are connected to the same workgroup.
From popcorn I am able to use the NAS server and shared folders from both PCs
From wdtv I am able to use Nas server but not the shared folders.
When I click on server I see the servers list (NAS in my configuration)
When I click on shared nothing happens, It doesn't show me the list of pc, nothing. It remains on shared icon.
I saw all the previous suggestions but nothing changed.