Hiya Mogget
I'm not 'au fait' with FSX keyboard commands I'm afraid but I'd have guessed at up/down arrows as default. I always have trim assigned to a joystick button which is much easier (for me). I haven't reassigned the buttons in FSX and these still work so I guess the command keys are the same between FS9 and X.
The only thing I can think of that will cause a swing on the ground and you have to fight it is a) a prop aircraft and the realism settings banged up to full or b) an engine out on a multi engined aircraft. You don't suffer a torque effect from a jet so the jet must be running with one or more engines out on one side. In the air, it's different as a fuel imbalance will cause an aircraft to turn to one side but this doesn't apply on the ground.
Hopefully, Brian will be in to give some guidance or a possible explanation as off the top of my head, I can't explain why you're not fired up with all 4 running right from the word go.
Do you start each flight with a default aircraft? Not doing so CAN cause problems (certainly in FS9 if not in FSX) so give that a go if you're not. I start each flight.. regardless of sim version.. with the default Cessna. Once the flight has loaded, I then choose which aircraft I want to fly (it's never the default Cessna)
ATB
DaveB
