please remove key--ignition disabled-anti-theft system enabled on 1991 Cadillac Seville

I put a new battery in my 91 cadillac seville, and as soon as i hooked it up, the computer in the car says "please remove ignition key, ignition disabled due to anti-theft system." But the key isn't even in the ignition! I've tried un-hooking the battery and hooking it back up, putting the key in and waiting, ect everything!! help!

2 answers
what did you have to do,pull the airbag,steering wheel, clock spring,,lock cylinder,and remove the two wires at the bottom on column of ignition switch(electrical part)? then install new key cylinder also?
I just had this happen to me, the ignition plunger actually broke. Does it feel like the key does anything when you stick it in and turn it? if it just feels like it is spining freely with no resistance, you are in trouble. It has noting to do with the batterie, but a broken piece of metal in the steering column good luck