If all the LPR are not listed when you view the Properties of your print server, you may have a conflict with a third-party print monitor.
You may also find that LPR is not an available option. If you usethe Spooler.exe is not running Lprmon.dll.
If an updated port monitor doesn't solve the problem, your only solution is to remove it:
1. Stop the Spooler service.
2. Rename the port monitor by locating it at HKEY_LOCAL_MACHINE\CurrentControlSet\Control\Print\Monitors.
NOTE: Renaming the port monitor is safer than deleting the key.