Application locks up when printing over the network via print server

I'm having sporadic issues with many users connected over the network to a print server. If the printer is their default printer the application used to print will freeze/lockup until they log out / restart their machine. The only way to fix this (from my experience) is to set their default printer to something else (like Adobe PDF) or bypass the print server completely and do it by direct TCP/IP.

Has anyone ever heard of this issue and know of a fix? Think it is a driver related problem?

right off the bat, it sounds like a driver issue or MAJOR dns issue. Are the default printer drivers PostScript by any chance? Are you offering both 64 and 32 bit drivers?

The printers are all HP mostly LaserJet 2055, and LaserJet 4100. The print server has the HP Universal Printing PCL 6 driver both in x86 and x64 versions. The driver version is the same: 61.104.12.7309. There is another driver: HP Universal Printing PCL 6 (v5.1) that no printers are actively using as far as I know... but I can't delete it because it says its in use by all the printers ???

The print server is Windows 2008 R2.

in order to remove the driver package you would need to stop the spooler service on the print server.

Are there any error messages in event viewer that point toward spooler or driver issues?

If the app on the user's pc locks up... Would seem the printer server is not releasing / acknowledging receipt of the print? Does this happen only when multiple people print at (nearly) the same time (and not when only one prints)?