John:
Have you had your electric service checked? You could have voltage supply problem (either too high or too low), or a bad/intermittent ground connection, or a bad/intermittent neutral. Contact your electric co. and tell them your tale; ask them if they will reimburse you for destroying your AC - fat chance, but it might encourage them to give the situation more than a cursory glance.
Oh, yeah - one other thing may be plaguing your supply - voltage spikes.
Luck,