I’m knocking on wood several times while typing this but things have been consistenly successful with Network Shares for a while. I’m not saying this will work for everybody but I for the last three weeks but I’ve had no network problems (no dropped shares, no invalid id passwords).
I turned off the master browser settings for all but one PC by setting the registry values as seen in this link
And having one consistent master browser has at least for now solved my issues.
I noticed once in the last two weeks that one of the WDTV’s set itself as the Master Browser. Things worked fine for a week but I decided to specify one PC as the explicit Master Browser. I ended up powering down all the WDTV’s (by unplugging) and then using the technet article to set the one PC as the Master