During cold weather it is common for the LCD panel to become sluggish or completely illegible. This is an inherent problem with LCD technology. To prevent this you must keep the hand controller warm. Some place the hand controller in their pocket, but obviously you can't move around much if you do. Another solution is to use a chemical hand warmer pouch that you can commonly find in the outdoors section of most department stores. Others use the Kendrick dew removal system, selecting the heater designed for the Telrad finder.
If you don't mind modifying your hand control beyond warranty, another solution is to mount two small resistors inside the hand control. Power for these mini heaters can come from the hand control itself. Visit the Astro Downloads page at Matthias Bopp's web site (http://www.dd1us.de) and read the article for the N5/8 or the N5i/8i electronic hand control heater.