Currently Being ModeratedJun 6, 2011 8:37 AM (in response to Graphic Designer, Tucson, AZ)
Uninstall all the Canon software, that is probably what is causing the problem. I would recommend using Canon's recommendations for removing their software. Then un-install the printer from the system using System Preferences + Print & Fax if it shows up. Then restart in Safe Mode, this will clear some caches. Then restart the computer normally and navigate to Print & Fax and re-add the printer.
If still no luck contact AppleCare (she's covered for 90 days for free) and they will help you walk through it.
Currently Being ModeratedJul 17, 2011 4:50 PM (in response to rkaufmann87)
Hi Roger - the problem was going from 10.6.7 to 10.6.8. That is when all of the printing problems began, as well as the wifi getting flaky. I was able to get the iMac speaking politely to the printer by installing Repair 10.6.8 and re-adding the Canon printer (see below):
Probably the single most common 10.6.8 problem, at least as evidenced by a massive 17 page thread in Apple Support Communities, is a failure to print. The typical symptom is that the printer driver software pauses, displaying a message that states something like: “printer-state-message="/usr/libexec/cups/backend/lpd failed" or “/usr/libexec/cups/backend/dnssd failed.” Not all printers have this problem, but users report seeing the symptom in a variety of different printers.
As is often the case with update-related problems, reinstalling 10.6.8 from the combo updater may eradicate the symptom. Another possible solution is modifying a printer file in the /etc/cups/ppd directory (as detailed in the above-linked thread).
Unfortunately, none of these solutions are guaranteed to work. What does reliably fix the problem is to downgrade back to 10.6.7. If you’d rather stick with 10.6.8, you can instead downgrade just the quartet of printer-related files that appear to be the root cause of the symptom. These are the socket, dnssd, lpd and ipp files, located in the /usr/libexec/cups/backend directory.
A Mac user wrote an application, Repair10.6.8 (direct download link), that automatically downgrades these four files for you. Several users report success with this program. After running the Repair app, you may also need to “reset printing system” by selecting the command from the contextual menu for the printer name in the Print & Fax System Preferences pane.
from MacUser 10.6.8. workaround articlehttp://www.macworld.com/article/160993/2011/07/1068_bugs.html#lsrc.nl_mwweek_t_c bstories