"Click to open" links don't work

I'm using Calibre 2.78 on OpenSuse LEAP 42.2. I had a previous install that was part of the distro (version 2.75.1); I removed that version and re-installed from the download link.

None of my "Click to open" links work (this was true before the upgrade also). They all fail with an error like:

------------------
Failed to open URI "file:///home/drawson/Calibre%20Library/Edward%20Abbey/Desert%20Solitaire%20(1163)".

Error when getting information for file '/home/drawson/Calibre%20Library/Edward%20Abbey/Desert%20Solitaire%20(1163)': No such file or directory.
-------------------

The directory in question does actually exist, permissions are normal. Note that the above URI's point to the directory, NOT the EPUB for the book :-((

Any suggestions?

Thanks!

Dan