Based on what you said you can access your files from Media Servers but not using Network Shares. You can try updating your WD TV to its latest firmware and verify that your folders are properlys shared:
http://support.wdc.com/warranty/policy.asp?custtype=end&lang=ls
If this does not fix the issue you may contact WD for a replacement, since you can use your Popcorn to access your networks shares.
