I've run Calibre in debug mode (both my normal installation and the new one). It doesn't look like anything interesting has come up

but here are the logs:
Code:
calibre Debug log
calibre 2.57.1 Portable embedded-python: True is64bit: False
Windows-7-6.1.7601-SP1 Windows ('32bit', 'WindowsPE')
32bit process running on 64bit windows
('Windows', '7', '6.1.7601')
Python 2.7.9
Windows: ('7', '6.1.7601', 'SP1', 'Multiprocessor Free')
Successfully initialized third party plugins: Extract ISBN && ADLIBRIS_SE && Unplugged && Modify ePub && User Category && ADLIBRIS_NO && Search The Internet && Resize Cover && Quick Preferences && Generate Cover && BOL_NL && Barnes & Noble && Job Spy && BOL_DE && LubimyCzytac && Favourites Menu && MultiColumnSearch && Reading List && Open With && View Manager && Count Pages && Author Book Count Hierarchy && Author Book Count && Walk Search History && Goodreads && catawiki && Quality Check && Manage Series && biblioNETka.pl && Find Duplicates
Starting up...
Calibre, and hence Job Spy, was gracefully shut down last time? True
Last time daemon started: never
Last time daemon failed: never
Total daemon starts inception_to_date: 0
Total daemon failures inception-to-date: 0
Job Spy has finished initialization...
[0] un-optimized number of undesirable characters accumulated: 759
calibre_plugins.multi_column_search.ui:211: UnicodeWarning: Unicode equal comparison failed to convert both arguments to Unicode - interpreting them as being unequal
[1] optimized number of undesirable characters accumulated: 660
Started up in 9.14 seconds with 2421 books
Code:
calibre Debug log
calibre 2.58 Portable embedded-python: True is64bit: False
Windows-7-6.1.7601-SP1 Windows ('32bit', 'WindowsPE')
32bit process running on 64bit windows
('Windows', '7', '6.1.7601')
Python 2.7.9
Windows: ('7', '6.1.7601', 'SP1', 'Multiprocessor Free')
Starting up...
Started up in 5.37 seconds with 1 books