OK... I got rid of the junction links and set up symbolic links instead.
May I ask a question that has nothing to do with Calibre, since you seem to know about these things?
The BIG folder on my C: disk is WinSxS. I looked into doing the copy-and-link-and-delete procedure, but found quite a few comments saying that this could be dangerous. I also found some comments saying that it works just fine.
Do you have any thoughts?