Potentiometer problems

[rachal]

We have a strange issue with our pots.
Situation:
The potentiometers are wired properly, Power to pin 1, Signal to pin 2, Ground to pin 3, and connected to a PWM connector. We have tried this with 3 separate potentiometers, and they work properly when examined with a Digital Multimeter. However, when connected to the Robot Controller, a strange thing happens. The potentiometers start out giving the value off them as 70, however their output rapidly drops down to around 40, and then starts dropping slowly. The drop appears to be a logarithmic function. We've checked that it's wired to the proper port, plugged in the right way around, wired to the right pins.

Is there anything you can think of that would cause this kind of behavior?