I have three Phidgets Touch Sensors hooked up to an Arduino Duemilanove. The sensors work fine with the exception when hooked up to Analog Pin 1. On this pin only, the sensor will work for about 5 minutes and then stop working, happens every time. Pins 2,3,4, and 5 are all fine and don't have this problem (didn't test pin 0 as I have a different sensor on that one). Very weird problem but I tested with multiple Arduino boards as well as multiple Phidgets Touch Sensors. The work around for my application is to simply not use pin 1 for the Touch Sensor but wanted to report this in case anyone has experienced the problem.
No great insights here except to suggest that perhaps the pin was damaged at some point. I found the A/D pins are VERY sensitive to overvoltage, and will still function as I/O pins but not as A/D pins if they have been subjected to illegal positive or negative voltages.
thanks for the reply but it's a brand new board. I also tested on another brand new board with the same results so I'm guessing some other issue.
Always welcomed .... 
All the best...