1990 Chevy Blazer Radio cuts out when doors open

First off, my radio's clock is messed up; every time I open the door the time returns to 1:00 and starts over from 1:00, when I'm traveling the clock works by telling the minutes that have passed, but when I arrive some where and open either door, the radio clock returns to 1:00.

Secondly, I can listen to the radio fine when on the road, but again when I open either door, the radio cuts to a different station that we never get and all the presets are erased.

What is going on and how do I fix these problems?