'Error Loading Mission'. What is this,please?

[gomer1969]

I am getting the same error. Switch planes and same message but with the new plane.

'Can't Find Sound Group Bob/Engines/Merlin III or invalid Set Up'

Anybody have any idea. It worked the very first time I tried to play. Then I exited to install my joystick correctly and know it won't work.

System. Going off memory as I am at work.
Intel quad 4, 4g Mem, Video card GTX660, Windows 7. Sidewider Joystick.

Is it the invalid set up part that I need to change something?