No interior electrical at startup...

I have a 2000 Malibu V6,essentially the Chevy version of your car, which also had started some weird behavior. The fuel gage and temp indicator wouldn't work after starting the car, as well as the heater fan, electric windows, rear defroster. After 5-10 minutes, some of them would work again - sometimes all of them. After compiling a list, I could see that all of the items affected were accessories that only worked with the ignition key ON. After asking a neighbor who works at a GM-Honda dealer (he's a Honda guy), he asked a few of the GM guys if it could be the ignition switch. They all said yes. So I replaced the switch assembly (list $140, discount $100) and it cured ALL of the problems.

OK - how does this link to your problem? The ignition switch has five major sets of contacts in it - in my case three of them were damaged/corroded from current arcing to the point where they restricted current flow. It's possible that the contact(s) in your switch that supply the affected systems are also damaged.

doug