WHS: The referenced account is locked out

After a brief, but entirely planned power outage that lasted for a good few hours, I discovered that the home PCs could no longer 'see' the home server.

Symptoms were an unhappy grey looking house in the systray, and any attempt to access the shares resulted in a cryptic message saying "the referenced account is locked out".. Remote desktop to the server worked, as did opening the server console.. 

Thankfully, there was a very easy fix...