Was using miles to book the IAH-DO and of course I ran into a CO.COM bug.

Was logged into my account and started the flight search (Reservations(from top toolbar) --> Make Flight Reservations). Went through and selected my reward travel dates. The final screen before purchase is "Review Ticket Details", at the bottom are three buttons (Continue, Reserve, and Back).

Selecting the Back button simply reloads the same screen without taking you back to select a different flight.

I tried this in both IE 7 and Netscape 7.2, same results. One thing I did notice though is it works if you are not logged into your account before the flight search starts.