Windows screwed up my ports - TeensyUser/doc GitHub Wiki
Windows stores some information like the port number it assigned to which combination of VID/PID/MI/SN of the device. This allows devices like Teensies to automatically get the same port number after rebooting or changing the hub port you connected it to. Sometimes (seldom) Windows screws up this information and gets confused.
- It might assign the same port number to more than one device
- It might not detect your device correctly.
Usually you can detect this error condition in the device manager where it marks those ports with a yellow warning sign. In those cases try to uninstall the device. Use the key combination WIN & BREAK to open control panel, look for the device in the device manager, right click and uninstall. After that remove the device from your usb hub and reconnect.