Firefox 35.0 is crashing for me, on both Windows 7 and Ubuntu (both 64-bit). On Windows, Firefox works fine but crashes every time I close the browser. On Ubuntu, it crashes when I open the browser, even in Safe Mode, but 34.0 still works properly without crashing.
See this - https://support.mozilla.org/en-US/kb/firefox-crashes-asking-support - KB page with each version of Firefox. The content of many KB pages vary depending upon the operating system version of Firefox you view the KB pages with.