There was a post from Supernova pool a couple of days ago saying they were going to close their wallet.

Problem with the staking is still apparent - the difficulty cannot drop any more than the current 0.000244 - if you have a small number of coins staking then it may take several days for them to build up enough stake weight to get a block. You dont lose out on any interest but its causing a problem still because the low block count means it takes a long time for transactions to completely confirm (needs 10 blocks).

If block production isnt back to normal in the next day or two I will look at releasing another wallet update to address the problem.