This is a spinoff of Bug 429184, which is for specific error messages that occur when printing. I'll have a draft for this shortly, but based on experience helping people the sequence should be: (1) Check your scaling, orientation, and margin settings. (2) Make sure you're printing to the right printer and not to a file. (3) Try to print from another browser. If it works, it's either the printer or Firefox. If it's not Firefox, try somewhere else for help. (4) If you have another printer (or virtual printer), try it. If it doesn't work either, it's (probably) Firefox. If it does work, try somewhere else for help with your printer. (5) Reset print.print_printer in about:config. If that works, quit. (6) Close Firefox, delete all print. lines from prefs.js, then restart Firefox. Notes: * I hesitate to include (6), but problems that (5) won't fix often require it. * Some printer drivers stubbornly refuse to work with Firefox. I've seen it with two models of Brother printers. One had an update that fixed the problem; the other didn't. * Some pages Just Don't Work in Firefox. They should be reported as broken.
The draft (bug URL) is up. It's named "Firefox prints incorrectly." We already have a page named "Firefox prints pages incorrectly," but it's a redirect to "Firefox prints pages in a different layout," which is a Firefox 2-only issue. I suggest we rename this to "Firefox prints pages incorrectly" and replace the redirect. I am not marking this FIXED yet pending comments on the prefs.js bit.
Evidently, I forgot to add the URL.
I'm closing this bug as invalid, because we don't track article requests in Bugzilla anymore. See http://support.mozilla.com/en-US/forums/knowledge-base-articles/705054