Stratus 6 / 7 keeps shutting off

Hello,
As the title implies I am having problems with my stratus radio. Recently it has started shutting off multiple times per car ride. Generally it comes back on very quickly, but on occasion it will shut off for an extended period of time (hours). I tried unplugging it from the power source for a period of time and reconnecting, however this did nothing.
I contacted Sirius and they sent me a newer radio (stratus 7). Today I hooked it up and within 10 minutes the same thing happened again.
Any thoughts what this could be?

Thanks for any help!

Its likely the power source in your car. Maybe your cigarette lighter is on the fritz.