Note that most CUPS filters produce temporary files in /var/spool/cups/tmp/. Can you check whether your disk partition is perhaps full and also what permissions /var/spool/cups/tmp/ and /var/spool/cups/ have ("sudo ls -ld /var/spool/cups/tmp/ /var/spool/cups/")?
Note that most CUPS filters produce temporary files in /var/spool/ cups/tmp/ . Can you check whether your disk partition is perhaps full and also what permissions /var/spool/ cups/tmp/ and /var/spool/cups/ have ("sudo ls -ld /var/spool/ cups/tmp/ /var/spool/cups/")?