Icom 7100 acting in a bad way

I have it installed in my S-10. The power and ground is in excellent condition and all connections are tight and fuses are good. I bought this radio new and used it as my base for several months and it did the shut down once as my base. Only once. I can listen all day with no problems at all. The minute I key up the radio reboots and settles back on the frequency it was on when it shutdown.
Other radios that draw four times the power do not malfunction when tested on the same power hook up.