[pablo2340]

I have some book files which are quite large (e.g. 7.8 Mb). My Calibre library is held in my Dropbox account. When I try to convert one of these book files to another format (it does not seem to matter what format), the conversion fails, with the error message:

calibre, version 1.26.0
ERROR: Unhandled exception: <b>IOError</b>:[Errno 13] File is open in another process: u'c:\\users\\paul\\documents\\my dropbox\\public\\pablo2340\\thomas cahill\\sailing the wine-dark sea (1800)\\sailing the wine-dark sea - thomas cahill.epub'

The details of the failure are:

calibre 1.26 isfrozen: True is64bit: False
Windows-7-6.1.7601-SP1 Windows ('32bit', 'WindowsPE')
32bit process running on 64bit windows
('Windows', '7', '6.1.7601')
Python 2.7.5
Windows: ('7', '6.1.7601', 'SP1', 'Multiprocessor Free')
Traceback (most recent call last):
File "site-packages\calibre\gui2\convert\single.py", line 278, in accept
File "site-packages\calibre\gui2\convert\metadata.py", line 236, in commit
File "site-packages\calibre\db\legacy.py", line 465, in set_metadata
File "site-packages\calibre\db\cache.py", line 57, in call_func_with_lock
File "site-packages\calibre\db\cache.py", line 1157, in set_metadata
File "site-packages\calibre\db\cache.py", line 1144, in set_field
File "site-packages\calibre\db\cache.py", line 945, in set_field
File "site-packages\calibre\db\backend.py", line 1357, in windows_check_if_files_in_use
File "site-packages\calibre\utils\filenames.py", line 370, in __init__
IOError: [Errno 13] File is open in another process: u'c:\\users\\paul\\documents\\my dropbox\\public\\pablo2340\\thomas cahill\\sailing the wine-dark sea (1800)\\sailing the wine-dark sea - thomas cahill.epub'

Would it help, I wonder, if I were running the 64-bit version of Calibre (which I THINK I used to have)?
If I close down Dropbox, the conversion goes ahead without a hitch...

Any ideas?

Paul