WASHINGTON (AP) — Technical problems at an air traffic control center in Virginia left passengers fuming as hundreds of flights to and from airports throughout a large swath of the Northeast were delayed or canceled.Miller Roberts of Dallas was trying to fly from Baltimore to Kansas City to set up a robotics display at the Missouri State Fair but was caught in a flight delay for more than four hours.Roberts, 40, said he boarded a Southwest Airlines flight Saturday that was supposed to take off at 10 a.m., but he was still sitting on the plane, waiting after 2 p.m.