Battery is good, but I'm probably going to replace it anyway, since it's the original AC Delco and it's going on 4 years. It's been doing it since I bought it in '05, and the dealer's response has always been -- everyone say this together now -- "we can't duplicate the problem."
It's so intermittent and unpredictable, it's hard to troubleshoot it.
I went out yesterday and cleaned the battery terminals and retightened them, then I pulled those fuses again and took a really good look at them, They have some normal oxidation on them but no corrosion. Fuse block sockets look fine. I cleaned the oxidation off the fuses and put them back.
When it happens, I have to pull both BATT fuses. Just pulling one or the other won't do it. Without fail, though, it starts right up after pulling the fuses and putting them back in. I don't know why I thought of doing that the first time it happened, but it works like a charm.
The next time it happens, if I'm not by myself, I'm going to get someone to hit the key and I'll tap on the starter/solenoid to see if that yields any results first. I'm still baffled by the fuse pulling fix. What am I resetting when I do that?
I thought about the iffy relay, but I changed that already. Same with the ignition switch.
I know these damn things have had electrical gremlins all over the place, and I figured it was one of those things that would take forever to track down. It gives us something to discuss and brainstorm, and I very much appreciate the feedback. Keep it coming.