Q: intermittent no start

Hello & thanks for your patient willingness to help me.

1. Battery is 2 months old, holds a charge & I don't think it's a weak alternator only because right now my Fluke meter reads 12.55+ volts & it's been sitting all day. Still, you'll know best.

2. It started fine at dawn, before parking after driving a bit to the store. Power locks, power windows worked, unlocked just fine & when I turn the ignition key all the appropriate warning status lights do come on. Continuing through to the click & that's it. One click, nothing happens, no crank.

3. The only thing after the 1 click that "happens" is the status lights go off, door locks don't work, even the headlights are completely dead.

4. Next, I use my Fluke to approximate the standing voltage & it's at 12.55 immediately.

5. After scratching my head a few minutes, I find the power locks work, & so do the headlights bright as usual.

6. Shut off the headlights, turn the key & the exact same scenarios from #2 & #3 repeats.
   My car has an automatic transmission.