2000 impala security message on and off intermittant

A couple of days ago I started the car and the security message appeared and flashed on and off with the red battery symbol. The radio locked up (display actually said "Locked"), and the red LED stayed on (not flashing). I turned the car off and on again and it stayed that way. I figured I would try to get home and worry about it tomorrow. Drove about 10 miles and after pulling into the driveway, shut it off and started it again, and no problems, everything back to normal. Then yesterday I was out driving and in the middle of the trip the security light comes on again. The radio stayed on and the LED didn't one, neither did the security message flash with the battery indicator. Just the security message. I called a Chev dealer and they told me it could be something dirty stuck to the key and to try to make sure the key is super clean each time.
Any thoughts? I'm thinking maybe their is dirt in the ignishen (sp?). What sort of repair bill am I looking at? Last time I had a itnermittant problem it was a severed purple wire that took them 12 hours and $1200 to find and $30 to repair. (Yes I took it up with Chev and got back 75% of the cost)
Any help at all is appreciated

A lot of people on this board (& me) are having problems w/ "PassLock." I had to take my car into the dealership & they replaced some part called ignition lock or something? And it cost $450.

What happens eventually is maybe your car won't start because if the Passlock goes it thinks your car is being stolen and won't allow the engine to fire up etc.

It's really freakin nasty.

I wrote a letter to Bob Lutz at GM corporate, and requested that he cancel all the extra electrical garbage like PassLock, and just have Chevy produce an honest car etc.

A couple of days later a secretary from GM corporate called me at work and thanked me for the letter and asked me how my car was doing!!!!!!!!!

I had enough money to cover the repair etc. so I just thanked her for her concern and begged some more for relief from all the extra electronic "extras" like pass lock.

Well, now my air conditioning just went. Haven't been to see about the security message yet. They can't fit me in till next Tues. My air was on fine and nice and cool and suddenly it was blowing hot air at me. I turned everything off and on again and fiddled, but no change. I just sure hope that it is one problem not a whole pile of problems. I was so hoping to get one or two more years out of this puppy. I just 2 weeks ago picked up a nail so decided to go ahead and replace all 4 tires with goodyear comfortreads and I love them. They are so smooth and quiet. The impala is so quiet anyway, and with these tires I end up waiting an eon for people to walk in parking lots in front of me cause they cannot hear the car at all behind them. So I am bummed. Hubby's jeep payments are done this March and I wanted to have a year with no payments, but if this is going to cost too much to fix, I will have to look at getting an new car while the employee pricing is on.
Does anyone know what the trade in value on a 2000 Implala is. It is the base model with a couple of extras like CD, leather steering wheel and 60/40 split rear seat. I've got 160,000KM on it and will be trading this canadian car in down here in Virginia.
Any advise about new cars and this situation is appreaciated. (Thanks to Mikeymike for your reply earlier! Gives me a little handle on pricing and what might be going on.)

...So in America when the sun goes down and I sit on the old broken-down river pier watching the long, long skies over New Jersey and sense all that raw land that rolls in one unbelievable huge bulge over to the West Coast,

...I think of employee pricing, I even think of old employee pricing, I think of employee pricing.

Just back from the Chev dealer and my car is fixed (I hope!) It was the BCM and it was affecting the AC and the security message and it had gotten bad enough that when the car started no gauges would function. The diagnostic and repair was $430. I was expecting the bill to be at least that much, so I feel pretty good about this now. Just so long as it stays fixed!
Thanks for this forum!

Well the security light came on a few times in my car before, but it hasn't come on if almost a year. It seems when it's really cold out that it comes on. Cars seem to do weird things when it's cold out. Sometimes my daytime running lights and the regular headlights come on at the same time, but again only when it's really cold out like 0-20 degrees out..

mike