Hi Francois,
It's been a long time since I haven't worked with the MC13213.
I remember experienced random freezes using the BeeStack (I don't have experience with SMAC).
Just before giving up on that front, we found a patch for the transceiver ISR that we never submitted to Freescale.
I attach the modified version just in case... Look for the CDA comment in MC1319xInterrupt.
Ciao,
Cristiano