2000 Intrigue - Major electrical problem

Driving my 2000 intrigue (110,000 miles) and all of a sudden every light on dashboard lit up as if car died and restarted in a millisecond or something, and the AC was suddenly on. It continued to do this, all the lights would light up and the tachomoter, speedometer, other gaugues would go haywire, then it would stop. REally scary, i can't drive it like this. Only thing different is about a week ago i changed the Emergency flasher switch (which was causing the turn signals not to work sometimes.) Any ideas?

UPDATE: 8/23/06
Thanks to you folks, I decided to check the battery. I found a bunch of junk (like battery acid, maybe?) on the terminal where the negative batttery cable grounds to the frame. (The small cable from the negative terminal grounded to the frame right next to the battery.)
I took out the battery and cleaned the ground terminal real good, scraping off all the junk, and cleaned the frame where it connects.)
Now it works fine! No cost, only about 1/2 hour of my time, AND (Thank God) no dealer to deal with.
I really appreciate all your help. This forum have saved me a bunch of time and money, since I have all the same problems with the Intrigue that everyone else has.

This happened twice to my wife in our '99'. I put a homemade grounding kit on and its been fine ever since - about 25,000 miles ago. I've heard others report that the alt might cause this also.

check those battery connections for corrosion or maybe a weak battery (battery load tester needed). Put a voltmeter on your battery and see if it's 12.6 volts.

I would take my car to the GM dealer and have them scan it with the Tech2. Having a OBD2 scanner for yourself would be nice also.

No codes, ses, svs light has never come on?

You can get a battery load tester for ~$25 at Harbor Freight and many auto stores. It can test output voltage of your alternator/electrical system also.

This sounds like what just happened to me tonight. My 2000 GL w/ approx 76000 miles started up fine in the driveway,then I drove to the store & shut it down. Came back out & it didn't start up,but when I turned the key to the ON position,the "ringer" was very faint,a relay was clicking faintly,interior lights didn't light-up except for the floorboard lights-they were very faint,radio did not work and the guages went haywire for a sec.
Went to jump it & all of the interior lights lit-up. Just when I thought it was all good & I had it made,I turned the key and.........nothing. Back to where it was before I jumped it.
I'll have to check and/or replace the battery & check out that Neg cable ground point on the frame (and check out some of the other ground points,as well) when I get it back to the house.

Thanks again for this great forum!