I've had similar experiences with my Cateye wireless. After I pedal away from a traffic stop, my cadence meter stops functioning until I reset it, very annoying. Purchased a Sigma 1909 STS last year, also a wireless model, to replace the Cateye. The Sigma computer is superb, I have absolutely no issues with this unit at all, anywhere.
Plus thier customer service is top notch, I still can't believe the trouble they went thru to get me a WHOLE NEW replacement computer when I had called them to purchase a button I was missing when my computer flew off my bike during a crash. Great products and even greater customer service!