Possibly Electromagnetic Interference. I am no physicist, but I found some info that might get you started on the right path.
http://en.wikipedia.org/wiki/Electromagnetic_interference
Calling all physicists! How does my computer interfere with my Chronos clock?
Sort:
Unbelievably, it appears that when I move my Chronos chess clock close to my computer the touch sensors stop working. Anybody know why this is? Does the computer radiate some sort of magnetic or electric field that interferes with the buttons?
A video is worth 1000 words: http://www.youtube.com/watch?v=GSwovvsyy7Q