Servos stop running on arduino due

Hi I am currently using the arduino due and after sometime of usage the servos just stop working ,it seems that it stops sending pwm signals to the servos after a while ,can someone explain y this might happen ??

Are you powering the servos using a separate power supply? If not, that is almost certainly the problem.

Yes I am using a separate power supply

Then, to get informed help, it would be a good idea to read the "how to post" sticky, and follow directions. Post your code using code tags "# button".