Our team is experience a problem where the 4 servos (which are all controlled as a group) lose their position when the drive train motors are used. Has anyone experienced this?

I took a look at the team's code and it seems fine to me so I am thinking this may be due to a voltage loss when the drive motors are activated.

The servos seem to recover inconsistently. If a servo value is set and not changed shouldn't it remain in the same position?

Thanks for any insight.

There is not enough information in your decription to tell what could be wrong.

That does sound like a low battery problem. Check to see if the servo controller isn't broken. Other than that, I have no idea. It would be nice to have a more detailed description of the problem.
I've found that if a servo stops responding, and you set it again, it recovers.

If the servos start to jump erratically when the motor is run, then the problem could be a bad motor. We had a problem last year when we started a sweeper to pick balls up off the floor, the robots servos started twitching. Eventually we swapped the motor out and the problem went away. If they don't hold position because they are overloaded, then obviously this won't help. Unless your battery is excessivly low, I wouldn't expect it to be a battery problem.