Error 13 when trying to update metadata

I am sure it is something I am doing, but it is becoming quite frustrating. As of the last update, when I try to bulk download and update metadata, (even on two books), I get the error message below:
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calibre, version 4.23.0
ERROR: Some failures: Failed to apply updated metadata for some books in your library. Click "Show Details" to see details.

THE LEFT-HANDED BOOKSELLERS OF LONDON - GARTH NIX

Traceback (most recent call last):
File "site-packages\calibre\gui2\actions\edit_metadata.py", line 821, in apply_mi
File "site-packages\calibre\db\legacy.py", line 472, in set_metadata
File "site-packages\calibre\db\cache.py", line 62, in call_func_with_lock
File "site-packages\calibre\db\cache.py", line 1321, in set_metadata
File "site-packages\calibre\db\cache.py", line 1316, in set_field
File "site-packages\calibre\db\cache.py", line 1118, in set_field
File "site-packages\calibre\db\backend.py", line 1520, in windows_check_if_files_in_use
File "site-packages\calibre\utils\filenames.py", line 410, in __init__
IOError: [Errno 13] File is open in another process: u'c:\\users\\mom34\\documents\\calibre library\\garth nix\\the left-handed booksellers of lond (416)\\metadata.opf'[/I][/B]

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The books are never open in another process and I have resorted to deleting all the new downloads from the file MY KINDLE CONTENT and it still doesn't work properly.

Any Help?

Thanks!!!

Karen