I am trying to use the Windows Print Queue Sensor to monitor the printer queues on my Windows 2003 print server. Most of the printers come up just fine but there are some that I keep getting this error message: Protocol Error: An exception occurred while populating the properties for the PrintQueue object. Win32 error. Access is denied. (code: PE023) I've tried changing the Windows credentials on the device, probe, root to every kind of administrator on my network (I even changed the login account for the probe service to the domain administrator) but nothing seems to work. I don't see anything obvious configured differently on the printer queues that work and those that error. If I use the WMI tester from PRTG it seems to access all the printers just fine with: Select * From Win32_Printer using all the different administrative logins I've tried. I even ran WireShark to see what is different and all I can see is that PRTG is using some kind of Windows Spool protocol to query the print server whereas the WMI tester does not. Any ideas on what else I can try to do to figure out why some printers are getting this error while others do not? Thanks!