I'm new here, so perhaps this has been answered earlier.  However, I wasn't able to find an answer by searching.  (If the answer is found in another post, if someone could please link to it it would be much appreciated.)

What's the situation with blocks such as #2861 in the "Block History" section of the BPM stats page where it shows "Block #" as 0 with an invalid blockexplorer.com link and lists the validity as "Confirmed" immediately?


Is that a real block, or a bug, or something else?  Is the reward for such blocks valid?

EDIT: Several minutes after my post (and about 20 minutes after the block first appeared in the list, saying "confirmed" etc.), the validity changed to "invalid."