Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

You can check for corrupted and duplicate fonts and other font issues:

• http://www.thexlab.com/faqs/multipleappsquit.html - Font Book 2.0 Help: Checking for damaged fonts
• http://www.creativetechs.com/iq/garbled_fonts_troubleshooting_guide.html

I opened a thread with the same question on bugzilla and was directed to focus on the Bizhub 360 driver. In Firefox 29 and later versions the combination of OSX7 and Konica Minoltas Bizhub driver 3.2 and later versions make Firefox crash immediately when trying to open the print dialoque box.

The problem was solved by upgrading to OSX9 and the corresponding Bizhub driver 3.5.2.

For reference: Bug 1048206 - Firefox crash and close when pressing Print button or Cmd+P