Honda cb750-not starting

So, I was about to leave for a week-long ride through the adirondacks today, and something went horribly wrong. Before leaving, I stop at the store to pick up some travelin' food. Everything is fine on the way over, and I park without incident. Fifteen minutes later, as I'm about to leave, I turn the key and nothing. No lights. No power. I used a multimeter to rule a few things out. The battery and main fuse are fine. There is voltage going through the starter magnetic switch, and the key ignition works switch works. My only thoughts are the regulator, silicon rectifier(not even sure what that is), or a bad ground. I don't know the best way to check those things, though. Any help would be greatly appreciated.  

Since you have a multi-meter let's start with a couple of questions.
I assume that you are getting 12V with the circuit on, so:
1) When you hit the starter button, what happens to the voltage? If it stays the same, that could indicate a bad starter switch, of a bad solenoid on the starter.
2) Does the voltage take a nose dive (like a couple of volts). That could indicate a bad battery, or a bad charging system. Hook up a trickle charger overnight, disconnect, and see if it starts. If it does... charging system. If the voltage still tanks, bad cell in the battery.  

Same thing recently has happened to me.  Nothing when I turn the key.  Can the key switch or cyliner be faulty. I am thinking the connection the key makes when turned is bad and needs a new key cylinder. Does this make sense on this bike.  Has anyone else done this with success?  Please help.