I downloaded the 7.3 Sigil, and tried it with another English book (I think this morning's was English too), similar problem:
Spoiler:
calibre, version 1.2.0
ERREUR : Exception non gérée: <b>UnicodeDecodeError</b>:'utf8' codec can't decode byte 0xc3 in position 0: unexpected end of data
calibre 1.2 [64bit] isfrozen: True is64bit: True
Windows-7-6.1.7601-SP1 Windows ('64bit', 'WindowsPE')
('Windows', '7', '6.1.7601')
Python 2.7.4
Windows: ('7', '6.1.7601', 'SP1', 'Multiprocessor Free')
Traceback (most recent call last):
File "calibre_plugins.open_with.action", line 178, in open_with
File "calibre_plugins.open_with.action", line 212, in launch_app
File "subprocess.py", line 711, in __init__
File "subprocess.py", line 907, in _execute_child
File "subprocess.py", line 646, in list2cmdline
UnicodeDecodeError: 'utf8' codec can't decode byte 0xc3 in position 0: unexpected end of data
PS: What is FWIW an acronym for? I knew only FYI.