I'm about ready to give up on wireless keyboards and mice. I have two different models of Logitech keyboards, and both of them occasionally take a break. I'll look up and see that it didn't enter letters or entire words. I've used different receivers and put them in different locations. The mice have the same problem. They sometimes stop working. Turning them off and on usually works.

One kbd is the Logitech K800 - brand new - and the other is similar, but it doesn't have the back-lit keys. The mice are M510 and M310. I've tried different mice, with the same result. One kbd uses batteries, and the other is rechargeable.