Why is my sound system shutting off?

I have a system in my car, buncha speakers, couple of subs, etc. The type of all this stuff doesnt matter. What matters is, when i hit my brakes, my system starts crackling and then shuts off completely so i have to hit reset on my head unit and re-do all my settings. Its not the way its hooked up and I know this because the system has been in my car for over a year. I did it myself, but i know its fine, ive installed more than one system before. This just recently started happening. Any ideas?