[FinallyGotOne]

+ 1 on the low battery. More often than not the batter is the culprit. I've had them where they seem to be strong as everything is powered up, but I cannot even get a click on the starter. The starter requires a LOT of amps to turn, the lights and radio and all that require very little.
I had a issue that turned out to be a loose negative cable. I would reach down and check and it appeared very tight as I could not move it, but then one day the cable was completely off.
weird, but once I rewrenched it back on tight, never had an issue again.