frequently fly FS2004 and undertake both

Are you talking switching flights or switching aircraft? If you are just switching aircraft make sure you have pulled the throttles back to idle, set the parking brake, disengaged autopilot, disengage airspeed hold and disengage the autothrottle before switching aircraft. Alternately you could shut down the engines before switching aircraft.Bud

Bud - thanks for response - problem has occured in a variety of scenarios (but only with my created flights) so: 1. I have deleted all my previous saved flights2. I will follow your advice aboveA brief check tonight reveals no problems so far. Thanks again - Roger

Definately make sure all of that stuff is taken care of before saving any flight :)Bud