Guys, sorry for my English, but I'll try to explain you something how it works. Look at the pictures. We have a private mining pool with huge mining power. How it works. It starts mining for short period of time when difficulty is low, as a result difficulty rises, and then pool shutdowns. That is why it takes too much time to find the block, because difficulty is high, and mining power is low. When block is found it starts mining again.
http://i.imgur.com/WiiI2IH.png?1http://i.imgur.com/ig7ugSL.png?1
