Trouble Starting

Hey I have been having a problem starting my Cherokee the past couple days. It would barely turn over, but last night it would not turn over at all. All the lights were bright and worked but when I would turn the key I would here a Pop noise and everything would shut off (lights, no response to key) So I tried that like two times. Finally I opened up the hood and I shook the battery cables and jiggled the PCM and it started? What could it be? Has anyone every experienced this? Forgot to mention its a 2001 Cherokee I'm going check out the cables today..

sounds like bad connection at the cables-- pop was probably arcing of electricity trying to jump a poor connection