I had a similar problem with EMI interference. I was running a practice race from the lower lift shack, all on battery power, and the times shown on my D-Line display kept jumping all over the place. As near as I could figure it, the long-ish run from my TIMY to the D-Line acted like an antenna and was picking up interference from the chairlift motor. I didn't figure this out until I noticed the times really start to jump when they stopped and started the chair. Shortening the cable seemed to do the trick in the short term, but I wouldn't want to have to rely on a timer for official results in that environment. There were no errors to speak of other than the odd displays, but it gives one pause.
On a side note, my Alge wireless system operated flawlessly at the same time. It's nice to have the flexibility to change training venues as the mood or hillspace issues strike. My Masters and Intramural leagues are definitely sold.
