Systems Management

Environment: Win7 x64 with Server 2003.
Multiple models of Xerox WorkCentre and HP m401.

Problem: Windows will randomly/intermittently be blind to printer drivers installed.

Scenario: Users try to print, but for some unknown reason, is unable to. When I remote in, I check printer properties, and then Windows spits out an error message telling me that the driver is not installed.

Observations:
1. when I go to Print Management, I can see that the drivers are in fact installed.
2. If a user discovers he can't print to his default network printer, printing to other network printers is also unavailable.
3. Reinstalling a driver for one revives connections to all.
4. User who's computer profile belongs to a different OU connected to the network here and had this problem (I say "had" because he was only visiting)
5. Don't know if the attempt to print at the moment triggers the problem, or if the problem happens before the attempt to print but the user discovers the inability to print at time of print attempt.
6. Moved one user's computer profile into an OU container that doesn't have any GPOs enforced. What's odd about this is that although it seems to be a fix, I can't see how a GPO could be causing the issue, because it should happen to all users in the OU at all times.

Speculations:
1. Possibly GPO-related, but I would think that a GPO would affect all users at the same time, all the time.
2. Windows update on one or more servers.
3. Windows update on affected user's machine in conjunction with GPO.


What I've done, but hasn't solved the problem:
1. Reinstalled drivers
2. Removed printer and deleted driver, then reinstalled printer.
3. Stopped and restarted spooler.
4. Checked Event Viewer, nothing consistent, but did find eventid 808, which is the entry for unidrvui.DLL failing to load.
5. Removed and installed updated driver

Anyone ever see anything like this? More importantly, does anyone know a fix?