Windows 7 Disable USB Ports While Windows is Shutting down

Hi
i have a PC with intel DH61WW Motherboard and windows 7 Ultimate installed on i and i have a USB Modem Connected to this PC, whenever the Modem is connected to this PC windows won't shutdown it stucks on shutting down windows and i turn it off by pressing the power button for 10 seconds but when i remove the usb cable from the PC and i shut it down it shutdown normally how can i make windows disable USB ports while shutting down?

thanks for the help in advance i am a new user here