[awake738]

same problem here with 0.6.12 - calibre process starts up but dies almost as quickly.. unfortunately I don't seem to have an older rev to hand...
output from calibre-debug is as below.. hopefully this means something to someone... ;-)

Traceback (most recent call last):
File "debug.py", line 10, in <module>
File "calibre\__init__.pyo", line 16, in <module>
File "calibre\startup.pyo", line 35, in <module>
File "calibre\utils\localization.pyo", line 66, in set_translators
File "calibreutils\localization.pyo", line 27, in get_lang
File "calibre\utils\config.pyo", line 23, in <module>
AttributeError: 'NoneType' object has no attribute 'special_folder_path'

this is on WinXP SP2 BTW...