Good evening folks!
First post here so hopefully its not too much of a clanger. My setup is as follows -
(NEW) PC upstairs plugged into netgear gigabit switch (Win 7 64 bit pro)
Laptop upstairs plugged into netgear gigabit switch (Win 7 64 bit Ultimate)
Netgear gigabit switch plugs into homeplug upstairs
WDTV live plugs into homeplug downstairs
Asus RTAC66u router also has a port connected to a homeplug downstairs
So on to the story. I had a decrepit old PC that used to house all my video content on a secondary internal hard drive. This PC sat upstairs as per description above and I would turn it on whenever I wanted to watch something on my TV downstairs via the WDTV Live box. So far so good all works fine and the network shares never dropped once. The only problem was that this PC was pretty much on its last legs, it had a good innings at being around 7 years old.
So I got myself a not too expensive but more up to date PC and moved the secondary HDD out of the old PC and into the new one. So the new PC is basically 2 x 500GB HDD, one being the boot drive the other being the storage drive. I setup all the necessary share permissions on the secondary HDD within the new PC and the WDTV live was able to see it as a media server but not a network share. I realised later that this was because the new PC was not on the same workgroup as the WDTV. Corrected this and voila! We can see the network shares, however I am stopped dead in my tracks when I browse to my content and try and play something…spinning orange arrow 
My WDTV live box worked absolutely fine until I got the later PC. I am thinking that maybe I should have just employed the though process of -
_ "If it aint broke, dont fix _ it"
What have I done wrong? Great Machine Spirit of the WD community please help me.
