Very odd. Why should it only occur in the fairly early morning? It's not happening now. Maybe it is my PC, or maybe a glitch caused by slow loading - sometimes pictures are very slow, and perhaps one or two in a single observation won't appear, though others do. Also, occasionally, the page displays oddly, with what appears to be background code appears alongside the expected text (e.g. - and this is an approximation, I can't recall actual details - "116N.User name" appears where I'd expect to see my user name.
Root and branch, very odd.