FIXED!!! There is a TSB #09-17/17 "Audio, Navigation and phone concerns with Mazda Connect Infotainment System". They basically just replaced the nav card I think. But since it's a TSB I think it's probably a free fix even if your car is out of warranty. Might be worth checking into at least. It was 9 degrees this morning and my radio did not reboot even once. Wahoo!
TSB's are not usually fixed for free out of warranty - that's just good customer service