Adafruit Feather nRF52840 Sense Win7/8.1

Hi, can anyone help with this? My shiny new Adafruit Feather nRF52840 Sense board is refusing to play ball with 2 out of the 3 computers I’ve tried it on. Each computer has a different version of windows (7, 8.1 & 10). With W10 I have no problems. With W7 and W8.1 the FTHR840BOOT boot drive works fine but on CIRCUITPY and when it is running an Arduino sketch I don’t get a COM port I just get “The drivers for this device are not installed. (Code 28)”.
Without a COM port I can’t connect to the Arduino Serial monitor or the Mu REPL.


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