I am running Calibre 7.57 with .08 enabled, however, I do not know when this issue originally started.
I have been using Calibre's Book View/Book Detail function to determine the number of pages for each book. I usually have my Kindle plugged in as a matter of course, but had just ejected it before downloading my latest e-book. When I went into book view I received the following error message:
Traceback (most recent call last):
File "site-packages\calibre\gui2\viewer\main.py", line 64, in run
File "threading.py", line 483, in run
File "site-packages\calibre\ebooks\oeb\iterator.py", line 195, in __enter__
File "site-packages\calibre\customize\conversion.py", line 204, in __call__
File "site-packages\calibre\__init__.py", line 391, in __exit__
WindowsError: [Error 3] The system cannot find the path specified: 'G:\\'
If I plug my Kindle back in, everything works fine.