I have had this happen five times in the last month.

One time was on a mixed CO/NW itinerary with an upgrade. It caused chaos on check in and I was fortunate enough to go in 2-3 hrs early when no one could give me a straight answer. I could not check in online, with the kiosk, finally the gate agent tried. It was not till they printed paper tickets that I could be checked in. Finally, the mileage did not post and it took several faxes etc to fix.

The other four times it was the dreaded SSSS. I seem to have gotten more then my share in the last 30 days.

ACVitale