Problem:
looking in /var/log/cups/error_log
E [28/Oct/2008:10:26:03 +1100] PID 6548 (/usr/lib/cups/filter/foomatic-rip) stopped with status 2!
E [28/Oct/2008:10:26:04 +1100] [Job 13] Job stopped due to filter errors.

Cause:
I think this was caused by me running sudo perl -MCPAN -e 'install CPAN::Bundle' and it upgrading just about everything. Then when the foomatic-rip filter runs (which I think uses a lot of Perl stuff) AppArmour denies it access to all the new modules which aren't part of the standard install.

Work-a-round:

sudo aa-complain cupsd

Links:
A nice complete how to fix it link ==> http://islandlinux.org/howto/upgrading-ubuntu-breaks-printer-cupsys