Sounds like a dual-puck ZO issue. A couple of years ago, my dual-puck system started to hunt dramatically for speed on occasion. Usually during early evening skiing. Trick skiing and slower jumpers were most noticeable. When it occurred, the system was only picking up 4-5 satellites. Other times it would get around 9 satellites and would be fine. Upgraded to the single-puck system and haven't had any issues.