You can avoid Fax Monitor pop-ups by turning it off.
To Turn Off Fax Monitor:
Go to Control Panel > Printers and Faxes.
Right Click 'FAX'.
Select TRACKING Tab.
Uncheck both Fax Monitor boxes for "Sent" and "Received".
The monitor is covered by any other program you click on. To view the monitor again:
a) minimize or exit from programs that cover the monitor screen, or
b) click on the Monitor icon at the lower right of your screen.