This is just a guess but could you unistall all three devices and reinstall starting with the USB modem first(preferbly plugged into a rear USB socket).
A friend had a problem with the BT USB modem which cuased the PC not to start up with it connected. He had to disconnect the modem, then start the PC.
He reinstalled the OS and plugged the Modem into a rear USB socket, then reinstalled the rest. the problem went away.