Network shared printers stop working; default printer changes

Question

Hello,
Have an odd printing issue that seems to be ongoing and am trying to come up with a good solution or fix for it.
We have an environment that has a Windows 2012R2 Print Server, that is sharing various printers which are also set to List in Directory.  Some of the printers are HP and are using the HP Universal driver which shows as "True" for Packaged in
the print management window, and some of the printers are Canon which are using device specific drivers and show as "False" for Packaged.  My understanding is that the packaged attribute simply indicates that Point and Print can then download
the driver and install/use it without any security prompts whereas if it is not Packaged, then the driver must be installed on the local server/workstation by an Administrator.  We have Group Policy defined such that all Point and Print restrictions are
Disabled.
We then have multiple Remote Desktop Session Hosts based on Server 2008R2 (x64).  Users connect to these hosts via thin clients (Wyse) and there is a domain login script using KiXtart that creates printer connections to the shared printers using an address
of \\printserver\printername.  We also set the default printer via the login script each time depending on user's group membership.
Each part of this setup is on it's own routed VLAN subnet, so the Print Server is on 192.168.0.x/24, RDSHs are on 192.168.1.x/24 and the printers themselves are on 192.168.2.x/24.  There is no firewall or other restrictions between the subnets, all traffic
is allowed to flow.
The issue we are having is two parts, the first is the larger issue, but both are a pain:
1) Randomly (no discernible pattern/reason/timeframe), some Canon printers will stop appearing in Print dialog boxes from applications when a user tries to print.  It only seems to happen on the Canon printers.  The printer will still show in Control
Panel -> Devices and Printers, but when you right click it and try to go to Printer Properties or view any of the printer settings, you'll get an error saying the printer is not accessible/valid.  I have also tried a WMI query for "select * from
win32_printer" and the printer will not be returned.  To temporarily fix it, we right click the printer, and choose to remove it and then go through the wizard to re-add the same printer from the directory again.  That will correct it and the
user can print again, view all properties, etc.  This doesn't happen to every user but happens sporadically and once it happens to a user it seems to pop up once every week or two.
Now, we have made a change and installed the Canon printers in question locally on the Remote Desktop Session Hosts themselves using TCP/IP ports so that each user logging into the session host will see all of the printers.  This also seems to have resolved
this issue.  So it leads me to think there is some sort of timeout or connection getting dropped, but for no real apparent reason.  This is all on a virtualized platform and so the Print Server and Session Hosts have very reliable LAN connections
amongst themselves.  And further, we never see the issue with the HP printers, they seem to maintain their stability at all times.
2) The other issue we are seeing is that from time to time the default printer setting changes or vanishes altogether.  It doesn't happen to every user but once it does happen it happens regularly (multiple times a day).  This happens even when using
the locally mapped TCP/IP printer or when using the network print server.  From what I have read and found, this generally seems to be a known issue regarding redirected client printers and some GP settings related thereto.  But we aren't redirecting
any local client printers, everything is network based/shared.
In digging into these two issues I have run across the following error we get regularly in the PrintService Event Viewer log:
The print spooler failed to import the printer driver that was downloaded from \\printserver\print$\x64\PCC\ntprint.inf_amd64_59246c3ac1bd3f2a.cab into the driver store for driver Microsoft enhanced Point and Print compatibility driver. Error code= 800f024b.
This can occur if there is a problem with the driver or the digital signature of the driver.
And digging further into that seems to be that their was an error validating one of the DLL files as seen at the following thread:  http://social.technet.microsoft.com/Forums/windowsserver/en-US/9fe186e4-52f7-4552-a223-b2320cfc9ed5/driver-install-semi-fails-with-800f024b?forum=winserverprint
We get the exact same error that is shown there UNISRV.DLL being flagged as invalid, and have applied the hotfix indicated in KB2701894.
I am not sure the above error is realted to the issues at hand, but figured it is a good starting point to eliminate it as a potential cause of the issue.
Any input or suggestions on what to do to diagnose or further resolve this would be greatly appreciated!

Answer 1

Alan, I'm getting this error 600 in my company. Is there any fix for this problem?
After installing KB2919355 on Windows 2012 R2, when I try to map a shared printer I receive the following error message: A policy is in effect on your computer which prevents you from connecting to this print queue. Please contact your system administrator.
If I uninstall the patch the shared printer maps correctly.
I also notice that if I copy the driver \\server\print$\x64\PCC\ntprint.inf_amd64_a7ac65d1b7714fb1.cab
from a Windows 2012 R2 before applying KB2919355 to the server that has the patch applyed (and rename it), I can map the printer.
Does anyone know if there is a fix for that?