i am facing some critical problem with my system using cygnal F124. it gets hang whenever any contactor goes off.

i use smps for 5V and an LDO for 3.3V
i gave one snubber across the coil of contactor.
i do not use supervisor ic for micro.
for reset i use RC.

out of three phase supply, one phase is given for contactor coil through relay ( 24V optocoupler used )
and another phase for smps.

but yet the problem is not solved.

how to suppress the spikes effectively please help me.

Haribabu