My computer does not boot properly when a USB device is plugged

Check the boot sequence for your PC under your PC BIOS. When the BIOS is set to boot from "other devices" that includes USB devices, computer would not boot if  USB modem / USB device is plugged into high speed USB port. To fix the boot up issue set the priority of boot to something other than "other devices" or change USB BIOS settings to enable automatic recognition of the speed of the USB device connected.