Since a few days i received the message (annoying sound alert from desktop during gaming!) that an USB device was not recognized.
Updating the USB drivers, uninstalling nor removing the device from device manager did do anything, after a restart the unknown usb device was reinstalled and then not recognized by Windows.
Long story short: hours wasted trying to find the cause.
The only thing that worked was to unplug the PC from power, five minutes or so. For some reason USB is always fed through the PSU even when the PC is shut off. So i thought let's break that line for a while and see if it helps. It did. Problem solved.