We have installed the Vexnet and everything works fine, its just when we try to use any of the motors we have attached with a heavy load going against them, the motors keep running for a second after we have stopped sending the control input using the transmitter. We have tried to reinstall the firmware, we have the back up battery and we have all the trim set to 0. Our robot battery is fully charged and we still had the issue. We installed everything over again even our program. This does not happen when we use Crystals and we are not sure what to do. Help!!! 
Note:
We are experiencing this problem on two different robots, so it is not an isolated issue. Also, we use Robot C to program. Could that make a difference?
Does this issue happen running the same code with no load on the motors? What programming software are you using?
when there is no load, it does not happen, it only happens when we have a load. we use RobotC software to do our programmimg.
First, make sure there is not a code issue by downloading Master Code and Default Code to the VEX 0.5 Microcontroller using our IFI Loader. Since you are using the VEXnet Upgrade, you must use the new “VEXnet Master Code ver 10” and “VEXnet Default Firmware”. All the files you need can be found on our Downloads Page.
we have always downloaded the new master firmware and the vexnet firmware. and it shouldnt be the code because we dont have any delays written in, we just have it so ports 1,2,3,4 are drive and are on the vexrt ch 2 and 3.
I understand but did you try it with the VEXnet Default Firmware we have on our web page using the IFI Loader?
Is the VEXnet LED blinking GREEN at a steady rate and/or does it ever go yellow. Seeing Yellow or a non-constant rate could indicate a poor VEXnet link which could cause the data transmitted to be delayed…otherwise you will need to contact our Tech Support for an RMA Number to return the unit.