The specified print monitor is unknown

Case 1: Installing a latest printer driver fixes the problem.

Case 2: Install the printer using local port and then re-capture as the sharing printer. Please check this link for more details.

Vista Print Issues

Many Vista printer issues are solved by installing the printer as a Local Printer. If you receive "access denied", check the permeations ...
www.chicagotech.net/vista/vistaprint.htm

Case 3: If you are running Vista or windows 2008, make sure UAC is no. You may need to re-enable the UAC.

Vista Security and Firewall

How to disable/enable Vista firewall using Group Policy How to disable UAC in Vista How to enable ICMP to reply a ping How to enable Vista Administrator account ...
www.howtonetworking.com/vista/vistasecurity.htm

Case 4: Try to use net command to cache the credentials first and then install the sharing printer, for example. Net use \\remotepcname \user:username.

How to re-cache credentials in Vista
http://www.chicagotech.net/netforums/viewtopic.php?t=2340

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