Finally some other people noticed.
It has been behaving strangely since this morning!
I bragged that I have lots of experience in mining, but what I see is a first for me,.. no EXPLANATION at all.
But I would bet its not a 51%, nor it is a FORK.
For 51% someone needs to take over ultracoinpool,....
I'm switching to ultracoinS please join me:
http://www.ultracoins.info/Thank you KingPin, if you have a lot of hashrate then it would be, out of precaution, a good plan to switch to a other dev pool right now.