I am working with an school trying to load print drivers on iBooks running OS 10.6 and 10.7. I loaded the latest drivers for the printers but found that they did not work correctly. I went to the Library and removed all the drivers and PPD's. When I tried to load the earlier version of the driver I get the message "A newer version of this driver already exist on this computer" and it will not let me load the driver.
I tried the same procedure on my personal MacBook Pro 10.8 and I can load and unload the drivers with no problem.
Any clues as to why this is happening?