Okay, I forgot to mention this last night, but I had a few problem trying to mine in the Caverns. I was in 'The Drop', and I attempted to mine the rocks there. Despite there being no other player in the location, attempting to mine around half of the rocks gave a message informing me that 'Someone else is mining this rock'. Some were fine, and I never got this problem in any other location, but it seemed odd, as I was very obviously alone.