Now I find all my built in SD card readers on the three computers (that survived the windows 10 update) still working have stopped working over the past few days. Damn. Still I can upload directly from the Camera.
Clearly I spoke to soon. Is this bad luck and a massive coincident or is there a SD card virus or similar data contagion out in the wild? I can't find any reliable reference to such a beast, at least at the moment.
So its off to replace my USB card reader and get some new cards, but keeping my fingers crossed.