My Ergonomic Keyboard stopped working randomly too, and the only way to get it working was to pull out the battery and putting it again, making the green light lights up and it will start working again. But after a while, it stops working so I need to repeat the procedure.Tried new batteries, using another USB port, another computer, trying to update drivers, restarting computer, and so on but nothing helped. My previous ones did the same thing and this is my 3rd replacement.
I noticed that whenever I put the battery again, the Calculator app always appears on my screen. I was confused but realized that the Calculator key on the keyboard was stuck! I got the key unstuck, the keyboard is now working normally for several days now.
I think the Ergonomic Keyboard stops working after a while (after a period of not using the keyboard) if a key is stuck. Try to press every key like the functional keys and figure out which one is stuck.