i am having a trouble about the phidget in processing.

I used Phidgets in Processing using phidget.21jar files from phidget website to run phidget in Processing environment.

(the latest version of Processing with one phidget interfacekit 8/8/8 w/6 port hub and two phidget stepper bipolar 1-motors in Window 7 system)

actually I built a system transferring the values from MS KINECT to Phidget boards via Processing.

(In short, MS kinect value >> processing>> Phidget motor control)

 

when the system was operating,

Suddenly the Phidget boards turned off and on again .  does anyone know why this problem causes? And could anyone explain me how can i deal with this problem ?

any comments or thoughts from you might be helpful for me.