The problem is that Firefox seems to be shrinking to fit a much smaller paper size?

If Firefox is not using the whole sheet of paper, this can be caused by having extracted the wrong paper size settings from Windows when reading the print driver data. Clearing it can involve finding some obscure settings, but here goes:

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the search box above the list, type or paste printer and pause while the list is filtered

(3) For each setting for the problem printer, right-click and Reset it. The fastest way is to right-click with the mouse and then press the r key on the keyboard with your other hand.

Note: In a couple other threads involving Brother printers, the preference printer_printer_name.print_paper_data was set to 256 and when the user edited it to 1 that fixed the paper size problem. If you see a 256 there, you can edit the value by doubling-clicking it or using right-click>Modify.

Any improvement?

By the way, your More System Details shows an optional settings file named user.js file in your profile folder (personal settings folder). Firefox uses the settings in that file at startup to override your saved preferences from the previous session. Unless you created that file yourself, it may contains settings from an add-on or external software. You can check and remove the file using the steps in this article: How to fix preferences that won't save.

If you find a file named user (of type JScript) but not user.js, Windows may be hiding file extensions from you. To work with files as accurately as possible, I suggest unhiding them. This Microsoft support article has the steps: http://windows.microsoft.com/en-us/wi.../show-hide-file-name-extensions.

Can you attach a screenshot?

• http://en.wikipedia.org/wiki/Screenshot
• https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem

• Use a compressed image type like PNG or JPG to save the screenshot
• Make sure that you do not exceed the maximum size of 1 MB