Ray P . I have managed to reproduce the bug and problems your post was about. Here is the sequence that did it. I selected the default cold n dark flight, then loaded the flight. Loaded up with no wheels suspended in mid air. I use REX weather by the way and have never had any problems with a clash between REX and FSX and sim models loaded of any other type.

I then changed aircraft reselected another paint and reloaded aircraft (This fixed a lot of problems with the 727 which used to load up firstup with problems with sound and switches, well it still does actually and always requires a reload) the wheels were back and looked ok. Made a few changes, EP on, opened the doors and put down stairs, plugs on etc, connected ground power and brought the ship alive electrically, then saved the flight as a separate flight with the intention of using it as a start up in Oz where I do a lot of flying. I use Avalon in Victoria because it has less scenery textures and is a relatively clear area and hence does not need much graphic and texture files to be loaded as say a large capital city airport anywhere else.

I then shutdown FSX, fired up FSX again, selected the B737-200, lchanged location to the cold n dark location. I then loaded saved cold n dark flight. Then if all fell apart so to speak. Program, textures and model took ages to load with weird graphics happening, it then loaded up correct model and paint but no wheels again, escape slide at rear deployed and stewardess standing in the cold so to speak, in other words the animated bits were all over the place and not selected or saved by me.

Cockpit required all switches resetting (again) and then I brought up the animation control, the animation control would not function then froze the program then the whole kit and caboodle crashed. Great. This is about as useless sometimes as the ACE loader which never changes anything on my models despite going throught the routine with it. No longer bother with ACE either.

Tried it again, same outcome with the same cold n dark default flight.

I have my traffic etc settings to the 16/16/16 rule which means minimum load in that area (As recommded by ORBX), I have no issues if I select the aircraft and then go fly now and it will load up with engines running and electrics and hydraulics etc to be activated and switched on, flys normally and ok after that no issues.

I think there is a clash between the animations control script and the saved cold n dark files and suspect the cold n dark files are somehow corrupted. Best not to bother with them from my point of view until Capt Sim comes up with a fix or some kind soul here on the forum has a suggestion.