Having read a few more forums where this problem is reported:
https://github.com/Ultimaker/Cura/issues/1022
It appears it is caused because unused USB card readers and probably built in ones, report that the drive letter exists but if you try to use it you get the error.
All that needs to be done is to test the drive BEFORE Windows can throw up the error. If the drive is not usable, then launch the programme without the previously used drive being read.