Quote from: alexrussel1980 on September 28, 2014, 07:21:10 PM

it happens when difficulty goes back to "difficulty" : 1.05594315,

I've had a look at my logs and this seems to be the correct period. Yours would be most or all of the PoW (+50, +400) blocks:

29-Sep-2014 05:09:49 1411931389 blocks: 532828 (+1) moneysupply: 9712419.304 (0) difficulty: 1.05594315 (0) 29-Sep-2014 05:12:39 1411931559 blocks: 532829 (+1) moneysupply: 9712469.304 (+50) difficulty: 0.68146369 (-0.37447946) 29-Sep-2014 05:13:27 1411931607 blocks: 532830 (+1) moneysupply: 9712519.304 (+50) difficulty: 0.45430913 (-0.22715456) 29-Sep-2014 05:13:31 1411931611 blocks: 532831 (+1) moneysupply: 9712569.304 (+50) difficulty: 0.45382149 (-0.00048764) 29-Sep-2014 05:14:09 1411931649 blocks: 532832 (+1) moneysupply: 9712619.304 (+50) difficulty: 0.459756 (+0.00593451) 29-Sep-2014 05:14:24 1411931664 blocks: 532833 (+1) moneysupply: 9712669.304 (+50) difficulty: 0.48865509 (+0.02889909) 29-Sep-2014 05:15:30 1411931730 blocks: 532834 (+1) moneysupply: 9712719.304 (+50) difficulty: 0.50049641 (+0.01184132) 29-Sep-2014 05:15:40 1411931740 blocks: 532835 (+1) moneysupply: 9712769.304 (+50) difficulty: 0.5259462 (+0.02544979) 29-Sep-2014 05:15:50 1411931750 blocks: 532836 (+1) moneysupply: 9712819.304 (+50) difficulty: 0.52257848 (-0.00336772) 29-Sep-2014 05:17:41 1411931861 blocks: 532837 (+1) moneysupply: 9713219.304 (+400) difficulty: 0.55227365 (+0.02969517) 29-Sep-2014 05:17:45 1411931865 blocks: 532828 (-9) moneysupply: 9712419.304 (-800) difficulty: 1.05594315 (+0.5036695)

The important things to look at are the relative adjustments in brackets; you can see the count of blocks increases by +1, then there's a -9 offset. That's the network preferring a better chain, in this case, a PoS block, which has much greater weight.

An adjustment killing off 9 mined blocks is unusual, but not impossible. Right now there seems to be a node in the US that is generating a lot of PoS blocks, which will result in more PoW orphans. I do mention in the OP that this coin can be a bit hard to mine... we're all in the same boat at the moment.