I have the same problem with KDFW since last fall. I was never able to get the problem resolved. UT2 traffic is at a standstill at the runways and FSX ATC never gives clearance for take off for the aircraft in front of me. What I end up doing is going into FSX "MAP" and return and the traffic disappears and I then can get clearance to taxi and hold, or take off. Or go into FSX realism setting and back and they disappear that way also. I don't like it because it ruins the realistic effects of other traffic, but it is the only way for me right now. But another issue I am having only with KDFW is that when I use FSpassengers, and upon take off roll with the PMDG 777, the passangers are in a complete panic for some reason and the flight approval rating drops to around 40%. This is only at KDFW and only with the PMDG 777, not any other add on aircraft.