Happened to me once this year. ORD-DEN, ONCI said see csr at airport, turns out when I checked in at kiosk it brought up 7 different flight choices under my last name and first initial (even though my full name was listed) when I chose my flight it said to call.
When I picked up the phone at kiosk they fixed it, but told me that 7 different people with same last name, and at leat first initial of my first name were flying out of ORD that day. That was the problem. They had it fixed within 10 seconds...no kidding.