Try the reset described here:
http://kb.mozillazine.org/Problems_printing_web_pages#Reset_printer

Thank you so much for your recommendation. The first try I simply did the one reset. Then, I realized I should go in and to the whole set for my specific printer. AND it works! I had been using Screen Grab to compensate all this time. Glad to have the ability to print directly from the web back. Hurray!

You're welcome. Please mark this thread as SOLVED.

I followed the above resolution and still have just blank pages... Is there a FIrefox Fix yet?

I have reset ALL my printer settings in the about:config window, but they don't stay. How do I get them to stay to what I set. Is there a confirm or update button somewhere?

How can I find preferences to rest printer. I type about:config and I a web page with different links. I can't find print.print_printer. This all strted when Firefox started updating from 3.6.9. Now at 3.6.15 and still prints blank pages.

about:config shouldn't give you a webpage. It is an internal page with hundreds of preferences.

Did you follow the instructions here?
http://kb.mozillazine.org/Problems_printing_web_pages#Reset_printer

I had same problem. Open Mozilla, Firefox from start, programs. Select open in safe-mode. Check box to reset user defaults, then go back and open Firefox normally.

^ Using that pref in the Firefox SafeMode is going to do a lot more than reset printer preferences. The user is going to loose bookmarks, passwords, site preferences, and more.

I reset my user defaults and did not loose bookmarks or passwords. And my printer is back working.

about:config did not show up. Only a webpage with Links all different and no pulldown menu.

See:

• http://kb.mozillazine.org/about%3Aconfig