I came across something interesting, I thought I would mention. I had my robot plugged into my computer and was working on the IR range sensor. This meant I was reading the ADC pin and had a DEBUG command in the code to show me the values I was getting back.
While this was going on, one of the robots arm was ...twitching... a bit, like the robot had suddenly developed Parkinson's disease.
While trying to figure out why that was happening I removed the DEBUG command statement and the problem disappeared.