Strange joystick behaviour

[Ivo de Colfmaker]

Hi,
I have some strange joystick behaviour,
When I start PSX  , regardless of the situation, the first touch of a button, and again, any button on the stick , moves my throttles forward .
Most of the time about, a quarter of it's full travel.
After that all is normal, untill closing PSX and starting it again, then the first push does the same.
Unplugged it and back in, same result.
Any ideas?
Ivo