Comment 42 for bug 488857

Jonathan: thanks -- so presumably there's something "stuck" in your Firefox profile that's making you default to Postscript. If possible, it'd be helpful if you could isolate whatever's doing that by doing something like the following:
  (1) backup your profile (tar czvf ~/backup.tar.gz ~/.mozilla/firefox/[your_profile_folder])
  (2) extract that backup to a temporary directory
  (3) delete chunks out of that temporary directory until you've isolated the file (or piece of the file) that triggers the bug.

(I'm guessing it's a line in "prefs.js" that's responsible, but I can't be sure)