Logitech trackballs

On my laptop at home I use a USB Logitech trackball.

On my PC at work I also use a USB Logitech trackball.

Within the last week, both of these trackballs began malfunctioning.

1. cursor comes and goes intermittently and then is completely gone

2. systray message pops up that USB device is not recognized


What could have changed in the past week ? Is there a Windows Update that
could have messed up Logitech trackballs ?