I have the same problem. but then with the wdtv live (not plus)
2x win7 x64.
-firewall disabled
-windows live essentials deleted
-disabled homegroups
but i doubt i has to do with the latest firmware. becouse i am running the 1.03.49 version and it dit work well for a month or more. but when i wanted to watch something on 12-24-10 it dit not show my win7 computers. but i can see and acces my NAS without a problem.