Kobo not recognized anymore

Hi All,
I hope that you can help me. I have two Kobo readers (Glo HD and Aura). Both used to work perfectly with Calibre, but since a few weeks they are not being recognized anymore.
I'm running Win 10 with Calibre ver. 2.49 and Kobo firmware ver. 3.16.576. Both readers are correctly recognized in Windows (drive letter assigned) and by the Kobo App.

Thanks!
Bart

Below is the detection debug log:

calibre 2.49 isfrozen: True is64bit: False
Windows-8-6.2.9200 Windows ('32bit', 'WindowsPE')
32bit process running on 64bit windows
('Windows', '8', '6.2.9200')
Python 2.7.9
Windows: ('8', '6.2.9200', '', 'Multiprocessor Free')
Successfully initialized third party plugins: DeDRM && KoboTouchExtended && Kobo Utilities
USB devices on system:
[u'usb\\vid_046d&pid_c531&rev_2100',
u'usb\\vid_0951&pid_16a4&rev_0003&mi_03',
u'usb\\vid_0781&pid_b6ba&rev_0124',
u'usb\\vid_045e&pid_075d&rev_0105&mi_02',
u'usb\\vid_045e&pid_075d&rev_0105',
u'usb\\vid_046d&pid_c318&rev_5500&mi_01',
u'usb\\vid_046d&pid_c318&rev_5500&mi_00',
u'usb\\asmediausbd_hub&vid_040e&pid_0100&rev_0000' ,
u'usb\\vid_2013&pid_0251&rev_0100',
u'usb\\vid_1058&pid_1140&rev_1003',
u'usb\\vid_05e3&pid_0605&rev_060;',
u'usb\\vid_0fcf&pid_1008&rev_0100',
u'usb\\root_hub20&vid8086&pid1e26&rev0004',
u'usb\\vid_0951&pid_16a4&rev_0003&mi_00',
u'usb\\vid_8087&pid_0024&rev_0000',
u'usb\\vid_1689&pid_fd00&ig_00',
u'usb\\root_hub30&vid1033&pid0194&rev0003',
u'usb\\root_hub30&vid8086&pid1e31&rev0004',
u'usb\\vid_0951&pid_16a4&rev_0003',
u'usb\\vid_2237&pid_4223&rev_0110',
u'usb\\vid_046d&pid_c318&rev_5500',
u'usb\\vid_045e&pid_075d&rev_0105&mi_00',
u'usb\\vid_1689&pid_fd00&rev_0124',
u'usb\\vid_8087&pid_0024&rev_0000',
u'usb\\vid_046d&pid_c531&rev_2100&mi_01',
u'usb\\vid_05e3&pid_0612&rev_9013',
u'usb\\vid_05e3&pid_0612&rev_9013',
u'usb\\vid_046d&pid_c531&rev_2100&mi_00',
u'usb\\root_hub20&vid8086&pid1e2d&rev0004']
Traceback (most recent call last):
File "site-packages\calibre\devices\scanner.py", line 85, in __call__
DriveError: No removable drives found
Drives detected:

No disabled plugins
Looking for devices of type: MTP_DEVICE
List of WPD PNP ids:
[u'\\\\?\\swd#wpdbusenum#{76fcb783-b200-11e5-8d77-74d02b25f149}#0000000000000000#{6ac27878-a6fa-4155-ba85-f98f491d4f33}',
u'\\\\?\\swd#wpdbusenum#{d25f6141-d8fe-11e1-aad7-00241d7da29d}#0000000000100000#{6ac27878-a6fa-4155-ba85-f98f491d4f33}']
No suitable MTP devices found

Looking for devices of type: SMART_DEVICE_APP
All IP addresses {'{0551CDD3-0BDB-482D-9353-3119FDB4A206}': [{'broadcast': '192.168.0.255', 'netmask': '255.255.255.0', 'addr': '192.168.0.169'}], '{EB995CFE-6C4E-11E5-8D6C-806E6F6E6963}': [{'broadcast': '127.255.255.255', 'netmask': '255.0.0.0', 'addr': '127.0.0.1'}]}
No device is connected

Looking for devices...
u'usb\\vid_2237&pid_4223&rev_0110'
u'usb\\vid_2237&pid_4223&rev_0110'

Devices possibly connected: None