Easydriver (stepper) and accelerometer (MMA7260Q)

suggest you change the stepper code to include a small delay

for(int i=0;i<steps;i++){             
   //loop through the number of steps that the stepper motor must complete
   digitalWrite(stepperPin, LOW);
   [glow]delayMicroseconds(500);[/glow]
   digitalWrite(stepperPin, HIGH);
   delayMicroseconds(1000);
 }

and rather than sleep (to disable the stepper)
why not use the Enable input instead?