Drivers, drivers, drivers
Good lesson learned. We finally got everything back up and running after a bit of hand wringing and suppressing our desire to go back to Panther. I have to say that the Apple rep was excellent and wanted to try every conceivable option. Good thing, as he was trying to find a common denominator with our systems. In this case it turned out to be our network printer. I have been meaning to write a review on the Brother 5540 network printer and have not gotten around to it, and it would still be a hearty thumbs up! Seems the Panther drivers did not like at all like Tiger, and once we had attempted to print to the Brother, the printing subsystem just went totally away. Fortunately, Brother has posted some new drivers which totally fixed the problem.
If you have experienced this, go to the Brother support website and search for Mac OS 10.4 drivers. There are 4 downloads, and at least 3 are critical. Before installation, open your Printer Preferences, click on "Add Printer" and at the top of the screen select "Reset Printing System". This will erase everything, but you can put them back, and if you are like us, you can't print to anything anyway. Install the TWAIN driver first, then the other two. Go back and add the printers in as needed, and all should be good!
So, the lesson is that no matter how good an OS upgrade is, it also depends on the other devices hanging off the system and any non-Apple software that controls it.
