Mine isn't syncing either. I'm stuck at block 15915 as well. Stopped about 18 hours ago, was working up until then. I hope this isn't a permanent stoppage. I have several hundred thousand coins in my wallet. And yes, I have the latest client.
So I got it to work. First make a back up of your wallet.dat file (If you haven't already), Then re-download the latest client just to make sure you have the right one. Then go to the "Roaming" folder (If you are using windows, if you are using mac or linux go to where ever that folder would be on that OS) and delete the whole thing. Then run the karma client and let it sync either past where it usually gets stuck or all the way doesn't matter, Then close the wallet and replace the wallet.dat that it generated with your back up and relaunch the client and it should be fixed.