ignition issue bcm?

Hey everyone, I've done some reading and can't find anything that describes my problem, so I had to ask.

200 alero. My sis-inlaws car. She's had it for about 6-8 months. Not many problems. Yesterday the car wouldn't start. I went over to see what I could do. When you turn the key to the on position, the headlights flash, gauges seem to bounce around. I can hear the fuel pump load up. When you turn the key to start it, everything goes dead. You hear the click of the starter/selinoid, but all power is cut off. Is this a passlock problem or some sort of shortin the bcm? I can get more info about the security light being on or flashing. I didn't even know wtf a passlock was before I got to this site. Thanks in advance for any help. It's her only car, I'd like to get it fixed for her w/o going to the stealership.

AHAAAAA!!!!!!
I called my sis-in law, to ask a couple of questions. I don't know why but I asked her if she had a different key. When she put the new key in she said it felt tighter in the ignition than the other key she was using. It now runs fine. I've had a key wear out on my chevy truck, but it just made me jiggle it until it turned the cylinder. I've never seen lights, buzzers and gauges act the way they did on her car. I also mentioned that the weight of a key chain may have made the key wear a bit faster or at least sit different in the ignition. She is getting another key made today. The key was already in the ignition when I went over yesterday, doh!!