Got in the '01 this morning and started it up. The dome and courtesy lights started blinking. WTF? They blinked maybe 10 times then stopped. Is this some sort of error code or something?

 

It likely is an intermittent short to ground in the courtesy light circuit. Either a pinched wire or a faulty door switch. My wife's company car just started doing it last week and it's driving her nuts. I almost spit my coffee out when she was telling me about her spastic dome light.

 

It really didn't act like a short. The lights were blinking as if they were hooked to the turn signal relay, blinking at a constant rate. on...off...on...off...on...off...on...off...

 

This is a video of the problem this individual is talking about. THIS IS NOT A SHORT. My 97 Blazer LT 4D 4wd started doing it today. This is an alert of some type, I am just not sure what.

Video of the Flashing Dome, Courtesy, and clicking without key in ignition.
Blazer dome - YouTube