flywheel diode question

view story

http://forum.allaboutcircuits.com – I am using this MOSFET to control a Solenoid and I have it protected with this diode as a flyback. However once and a while I will still get a MOSFET to short from turning the coil on and off. Oddly the Diode is still fine. Do i need a Larger Diode? the voltage level on the coil is +12v This is the basic configuration, Imagine the Lamp as a coil. I should also mention that the Diode is internal on the board with the MOSFET and the coil is external. THANKS! (Embedded)