Hi Etienne,
I see what you meant.
All my USB sticks are USB 3.0 and they work fine with my USB 2.0 to VGA display adapters without frozen screen issue when powering Genos off. Your problem now seems to be isolated to your ITEC USB2HDTRIO USB 2.0 to VGA display adapter.
I have always been using a PNY Turbo 256-GB USB 3.0 flash drive on the front USB port of Genos, and the Startech USB2VGAPRO2 USB to VGA adapter on the back USB port of Genos simultaneously without any frozen screen issue when powering off my Genos. With this configuration I rebooted Genos for more than a hundred times without frozen screens.
I specifically tested for you the following scenarios with USB 3.0 stick remained plugged in the front USB port of Genos at least 4 times per test case, but all without frozen screen when powering Genos off:
1. Directly connected Startech USB2VGAPRO2 USB to VGA adapter to back USB port of Genos
2. Connected a non-powered USB 2.0 hub to the back USB port of Genos, plugged the USB2VGAPRO2 USB to VGA adapter to port 1 of the USB hub
3. Connected a non-powered USB 2.0 hub to the back USB port of Genos, plugged the USB2VGAPRO2 USB to VGA adapter to port 1 of the USB hub, connected a USB flash drive to port 2 of the USB hub
Perhaps I should also mention that I extended the testing by plugging USB flash drives with different capacities, e.g. 16GB, 32GB, 128GB, and 256GB, only one at a time, to port 2 of the USB hub at the back USB port of Genos. When Genos got powered up, these USB sticks became USB1, making the USB stick plugged in to the front USB port of Genos changed from USB1 to USB2, which made the Yamaha supplied playlists stopped working. So, it is a bad idea to have a USB stick installed at the back USB port of Genos.
Auto Power Saving and Auto Power Off features never work on my US Genos. As a precaution, I actually disabled both to prevent any possible unwanted data corruption associated with Auto Power Off.
Thanks,
Paul