That sounds like a complicated problem and it is not easy for me to troubleshoot with the limited information I have about your system, but I can recommend a few things to check. It is possible that the behavior you described could be caused by a brownout, which is a drooping of the supply voltage as large amounts of current are drawn briefly. You might consider adding some electrolytic capacitors across the sensor power rails to ensure they have a clean power supply. You might also check to be sure your signal wires are not in close proximity to the high current wires for the motors.
If your motors and the sensors are run from the same controller, you might try putting together a simplified test program to test whether a single motor and sensor (using the XSHUT pin) operate at the same time and gradually making the system more complicated again until it fails.
-Nathan