Hi all,
I appreciate your assistance very much. My system is now back to normal with both keyboard & mouse working.
I tried everything suggested by posters, most times repeatedly.

The transceiver device was originally plugged in to the back of the computer box, about 4 feet below the desk. I moved it to my LCD monitor and plugged it into 1 of the USB ports there (now about 16" to 24"). I think the proximity of it to the signal sources (keyboard & mouse) makes the difference.

Once again thank you to all. FT is an awesome community ^