Is difficult to say, but seems that there´s something wrong in the printer installation, as you cannot even print ps files, with which programs do you get prints?
Have you tried to disinstall the printer and reinstall it, it happens that sometimes cups gets mad for ununderstanding reasons, the only way is to rebuild the printers list.
Another thing, do you use the right ppd for the printer? take a look at
http://openprinting.org/printer_list.cgiciao
luca