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Janeygee - Can you confirm which version of calibre you installed? I'm assuming the regular or 64 bit version - portable is a bit different. And can you confirm that the spinning disk drive is drive D: - the DVD drive is more often assigned to D: on Windows systems and the extra disk drive would be E:
Is the "Calibre Library" listed under the
Remove library item in the library icon drop down? If it is then remove it via the
Remove library option - don't worry it wont delete anything, it will open a File Explorer window, just close it.
Now go to the Create/Switch options and use the blue button to browse to the library, and make sure you have selected the first radio button.
If that doesn't work, then I suggest you start from scratch following these
instructions from eschwartz,
But first you'll need to remove the library, and the calibre configuration folder and uninstall calibre.
BR