Photoshop :: Saved Printer Information Is Not Compatible With CS5.1?

have approx 500 Windows 7 64bit machines with about 600/700 users - 200 machines have the CS5.5 Master Collection installed on them. We have an intermittent issue with printing from Photoshop (both the 32bit and 64bit versions). Our printers are mostly HP LaserJet printers (all modern), but we have an Epson B-510DN Inkjet and some Xerox copiers too. The drivers are all installed on a central print server running Server 2008 R2 and shared via Group Policy to client machines.
 
In rooms where Photoshop is installed, intermittently when a student goes to print we will recieve the following error:The saved printer information is not compatible with this version of Photoshop, or the saved printer is no longer available. You will need to check your printer settings before printing.Photoshop will then grey out the 'Print' button and won't let the user print again. The odd thing is that we can still print from other software such as Microsoft Word or even non Microsoft software - even Illustrator will print. It just seems to be Photoshop thats has any issues.
 
This happens when printing to any printer on site, 90% of which are HP's. As a general rule we configure all of our HP printers with HP's PCL6 Universal Print Driver as it makes management of various printer models easy, and we haven't found it to limit us atall yet. We are aware the Adobe software is 'preferential' to Postscript drivers but our printers arn't, being HP's PCL is their native language. We have tried changing a printer to the Postscript UPD driver to test it but it made no improvement. We have also seen the issue quite indepth with our Epson B-510DN which is configured with Epson's latest model specific driver as our photography department use it. Since we are seeing it with different printers I don't believe the printer drivers are to blame.
 
Like I say the problem is intermittent, and we are having trouble tracing it down to a user, computer or a software problem as it is so intermittent. Since it's only happening in Photoshop is it a bug that Adobe have recognosed and fixed in CS6? The only workaround we have found for it is to go into printers, chnage the defualt printer from one to another and back again - this seems to shut Photoshop up.