United Airlines is blaming the failure of its reservations computer for dozens of flight delays.
Spokesman Jeff Green says the 45 minute computer breakdown affected at least 54 domestic flights, mostly those flying into or out of Chicago and Denver.
Delays lasted as long as 70 minutes, but averaged 20-to-25 minutes.
United attributed the breakdown to a server connection problem.
Chicago's O'Hare International Airport and Denver International Airport are two of five main hubs for United.
The airline is the dominant carrier at DIA, and has thousands of employees in Colorado.