The Hwire lib hangs, since it enters an endless loop. (see my post hier http://www.stm32duino.com/viewtopic.php?f=14&t=462)
The wire lib hangs too, if the SDA pin does not go HIGH. It s because the polling function of the SDA pin has no exit condition, if the SDA does not go high.
Did you find a solution for your problem?