Well I've had the same issue once with UA and my interaction with their "security department" was idiotic at best. I was in TLL attempting to ONLCI for my return flight when I got a generic "your account is disabled contact security" message. After arriving home I contacted security and was told they detected logon activity from a suspicious IP address in Estonia. After a short conversation explaining that was me the UA person replied that they had no way of determining the activity was me. I replied they did. All they had to do was take a look at my current itinerary.