amanoffewwords: Do you have a cordless mouse or keyboard - 'cause that message appears on my logitech every once in a while. prolly when the radio contact is broken/repaired.
Bingo! Yes, I'm using a Logitech wireless keyboard/mouse combo. That must be it.
But I've got Liam's and Richard's suggestions downloaded and printed already too, so I will go home and have a go at those just in case.
Many, many thanks!