Printers suddenly disappeared from my printers list, won't re-install.

Question

I have an iBook G4 1 Ghz with 512 MB ram, 30 GB hard drive. There is a lot of hard drive space available, and the machine is running OS X 10.4.9.
I have two printers I use with it: a Canon S600 inkjet printer, and a Samsung SPP-2040 dye sub photo printer. Have been using the S600 with no difficulty since I got the iBook new 3 years ago, and have used the Samsung many times in the few months we've had it.
Suddenly today, both printers have disappeared from iBook's printer list. If I click on "Add printer", the S600 appears in printer browser window, but the Samsung does not. When I highlight the S600 and click "Add", the message "An error occurred while adding the selected printer" appears. No hint as to what sort of error is offered.
In Print & Fax in System Preferences, no printers show up on the list. Hitting the "+" on that list will show the S600 in the browser window if the printer is connected and power is on. But I cannot add, it just continues searching for the driver.
So, I went to the Canon website and downloaded the S600 driver for OSX (though it should already have this driver; it has been using this printer for years!). Installation then stalled. It said "finishing up" and that it would be done in "less than a minute", but that info was on the screen for almost 20 minutes before I finally just restarted the machine. (I was otherwise unable to escape/abort the install.)
I have not tried to re-install the Samsung printer; it was harder to install in the first place and unlike the S600, it doesn't even appear on the list when I browse for new printers.
Does anyone know what would cause this problem and/or do you have any solutions to suggest? I have not recently downloaded any updates or software that may be messing with my printer settings. The laptop and printers are turned off when not in use, and I have already tried restarting all of the devices.
Any clue? I'm stumped.
iBook G4 1 Ghz 30GB 512   Mac OS X (10.4.9)   Samsung SPP-2040, Canon S600

Answer 1

I downloaded the Printer Setup Repair shareware and have been playing with it for a long time. The problem appears to be related to the cups process. It is set to load at start up, but the shareware says it is not running. It says to check permissions. When I do that, the shareware says there are no problems with the cupsd permissions. There is an option to reset everything, but the warnings are too scary.
I have also tried Disk Utility and re-installing CUPS.
This is extremely frustrating. I am not impressed with Apple at this point. I'd consider calling Apple for support, but my machine is 3 years old, no longer under warranty, and I don't wish to pay them $50+ for a phone call because their automatic update process messed up my machine!
Any other suggestion?