I worked on a printing problem today for a user. This is Windows XP. For any network printer that was an HP LaserJet P2015 in her list she could not print to it. If you right-clicked on the printer in the list and chose properties you would get the following message "The specified printer driver is currently in use."
If you opened the Print Server Properties page and tried to uninstall the printer driver you could also get an error message saying he could not uninstall because it was in use.
To resolve this I first deleted any network printer that was an HP LaserJet P2015 from her list of printers. I then stopped the print spooler service. Then used regedit and went to the following registry key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Environments\Windows NT x86\Drivers
and deleted the reference to the HP LaserJet P2015.
Then restarted the Printer Spooler service. Went to the Print Server Properties page (click START, Printers and Faxes, then in the menus click on File, and then Server Properties). Click on the drivers tab and choose to add a new printer driver. Once the driver was installed I reattached the network printers and had no further errors.
Thanks to the following website for help locating the registry key above: