Remove the line JOY1_HATUP=CAM_ROTATE_UP from the f18keys.ini file
Thanks, Rudel, I'll add this to my JF/A-18 archive, unfortunately I've just realized DXTweaker doesn't work under Win7 x64, and DXTweaker was the essential utility, that kept this game up for a long while for me. Also I'm not able to roll back to WinXP sp3 on my current hardware.
Cheers,
Dirk.