We ran into this problem, made some changes to the Devices and Printers configuration and got it working. Try this.
Here is a quick blurb about the fax printer install fix:
Troubleshot Network Fax capabilities on Windows 7. Make sure you have admin rights on the computer.
Removed all other Fax devices from customer's PC
Installed Hotfix on customer's system
Try reading the fax printer (http://192.168.1.3:631/printers/faxprinter
If, when adding, you get a prompt for user logon that does not work or a small printer related window pops up asking for the Standard TCP/IP port Monitor window, apply the following remedy.
Opened Devices and Printers
Selected a printer from the list - this makes 'Print Server Properties' show in the tool bar
Picked 'Print Server Properties', go to Ports tab
Looked through the list and removed any orphaned ports labeled 'http://192.168.1.3:631/printers/faxprinter'
Close and try reading the printer again. This worked for us.