tms470 emc reset
Some time ago I solved a similar problem involving a PIC that was switching relays.
There were two problems - the PIC went into latch-up due to the commutation
disturbance and then was unable to recover from the latch-up due to a bad design
of the power supply.
I corrected the power supply and improved the noise immunity of the PIC and
the design is impossible to disturb now.
So my suggestion to you is to first check the power supply design.
If you could post the schematics and PCB layout I could have a look at it.
Or mail it, if it is confidential...