Shut down your computer and double-check your modem
connection. Remove any other USB devices currently connected and ensure
the modem cable is firmly connected in a USB port which you are sure is
working. If your modem is connected via a hub or other power management
device remove this and connect the modem directly to the computer.
The following diagram indicates the sequence in which the modem should be
connected to your computer:
Then restart your computer and retry connecting. Once the
computer has completely loaded wait 30 seconds to allow the modem to
synchronise before attempting to reconnect.