The Pending fax message in the Outgoing Fax panel passes to the Sending Fax panel automatically, but quickly, it moved back.

• Some other process has the port Open. Look for any running app or Service (such as the Telephony Service -- Windows Fax and Scan or the RAS Service) that might have the port open, and disable this service.

Or

• The port was left in a bad state and cannot be opened. For external modems, power the modem off, count to 10, repower the device. For internal modems you must reboot the machine in order to guarantee a reset.
  
  Hyperterminal Test - After doing the above, try this:

Open Hyperterminal (Start - Programs -> Accessories -> Communications)
1st Dialog: Give the session some name: "foo"
2nd Dialog: Connect using the COM port NOT the modem name
3rd Dialog: Accept all the default settings.
Once you are in the terminal window, type "AT" and hit ENTER