promblem with all fs9 aircraft

hii have just been on fs9 and i was using real world weather at boston hardly no winds at all and when my cessna was going down the runway at bout 20 knots it just started to turn quite sharply i was not tuching the joystick or pressing the keyboard to move the rudder or anythin it just started turning and then when i try something to set all rudder back to normal nothin happend this also happens on every aircraft on fs9 including add ons like idfg and posky can anyone help. and when i go to the same airprot with the deafault weather it still just turns .this has only just ocurred after importing some american eagle flighplans into ultimate traffic can anyone help also this happens at every airport in the fs9 now hope you can help thanks in advance jimmer