Ubuntu :: Suddenly Can No Longer Print ?

I have no idea what happened, but as of around a week ago, I can no longer print in Ubuntu 10.04.

The printer is a Brother MFC-7440N connected to my LAN. I have never had a problem before printing to it from any of my computers, regardless of whether they were running Windows XP, Windows 7, or Ubuntu 9.10 or 10.04. I am still able to print from Windows 7, so I'm reasonably sure there's nothing wrong with the printer or network configuration.

But I can't get it to print at all from Ubuntu. I already tried reinstalling the drivers and re-setting it up in CUPS - no change. Every time I try to print a test page, the printer does nothing, and "Document Print Status" shows the job as eternally "Pending."

If I go to the CUPS printer page [url], the job status shows as "Paused - "Unable to locate printer 'MFC-7440N'!"

I don't know why CUPS thinks it can't locate the printer. When I was setting up the printer in CUPS, CUPS properly detected it on the network, no problem.

I can see the printer in the CUPS administration page, and even change settings. The one thing I cannot do is get it to actually print!

Like I said, the printer works fine through Windows, so I think this is an Ubuntu problem, not a printer problem.

When I open "System->Administration->Printing," there's an icon of the printer with a green-circle check mark, as if everything is OK. But if I right-click, the "Enabled" box is not checked. Checking it myself has no apparent effect.