OK this is my theory, looking at my potcoind logs at around 11:20GMT we have 30 blocks all accepted within 3 mins, the result of that knocked the diff way up ..... and we are still waiting for it to recover.
See here:i can't explain it and am trying to figure out why this is
all block after orphaned are unconfirmed and why they get orphaned?
2932 2014-04-23 11:34:02 Credit Unconfirmed 196781 1.68617352
2856 2014-04-23 11:00:03 Credit Unconfirmed 196740 3.63813799
2817 2014-04-23 10:10:04 Credit Unconfirmed 196708 7.44090005
2772 2014-04-23 08:48:02 Credit Orphaned 196579 2.44060202