Mac OS X 10.5.5: USB connected printers do not print; printer queue displays "Printer is currently off-line" ...
... After updating to Mac OS X 10.5.5, you may not be able to print to some USB-based printers. This message may appear in the printer queue: "Printer is currently off-line."
... Open this link in a web browser: (http://localhost:631/printers/) Click the "Modify Printer" button for your affected USB printer queue. Click Continue. You may need to wait a few seconds. From the "Device:" pop-up menu, select "Unknown USB". Click Continue. The "Make:" list should highlight the manufacturer of your printer. Click Continue. Select the printer model that is attached. Click "Modify Printer". Enter an administrator account name and password....Alas, that 10.5.5 measure didn't work, though it's nice to know that localhost:631 interface to the CUPS printing service. Maybe 10.7 is better, but I'm trying to avoid that mangy beast.
I had past success with the networked Brother MFC-7820N - I only gave up on it when the print mechanism started jamming (old). I figured when my next printer cartridge was due I'd look for something better. Alas, we're WLAN these days, and the reviews for Brother's wireless printers are not good. In fact, there don't seem to be any good reviews for anything. Printing is fading away.
So instead I disconnected the printer from our 10.6 iMac and connected it to an old and underused 802.11G Airport Express. That did the trick. It's been two weeks and the 2140 has been working for all of us. Cheaper (free in our case) and more reliable than a printer WiFi client.