Calibre 4.x no longer starts

Hello,

Since the new version 4.x, Calibre no longer starts.
Below are the traces in a DOS window:

C:\Program Files\Calibre2>calibre-debug -g
calibre 4.4 embedded-python: True is64bit: False
Windows-8-6.2.9200-SP0 Windows ('32bit', 'WindowsPE')
('Windows', '8', '6.2.9200')
Python 2.7.16+
Windows: ('8', '6.2.9200', 'SP0', u'Multiprocessor Free')
Interface language: fr
Turning on automatic hidpi scaling

C:\Program Files\Calibre2>

On the other hand no problem with version 3.48

Thank you