Zinga Poker Login Problems

Over the past couple of weeks, I have been unable to log in to play poker, getting the "connecting to your poker buddies" screen and never getting further.  I have been playing the game for months now and this has just started to happen.  The only way that I can play is to shut down my ipone then turn it back on. I have to do this every time I want to play a game, even if it is in the same day.  I need to find out why and fix this problem.  This only happens on Zynga Poker