battery problems??

I own a 2000 chevy blazer and its hard to
explain what happens to it but as I drive it
its almost like there is a power cut off? It
only happens when I begin to press on the
break and the radio will cut for a second
and all the idiot lights will flash on and the
gadges will smash down to zero and then
the battery light shuts off and everything
goes back to normal. I would have never
noticed it if the gadges didn't swig
extremely fast back and forth as the power
restarts. I tried explaining it to my
machinist but he seemed to believe that
the car wouldn't leave me stranded. Is this
something I should just ignore or go further
into looking at this strange action? Also i
had to jump start it but that was a few
weeks ago and this only started happening
now could a jump start screw up the car
this much?