Firefox always develop their browser software into new version. Except launch final version, Firefox also launch beta version for public testing. The newest beta version of firefox is Firefox 3.6.4 Beta that you can download by free
Firefox 3.6.4 provides uninterrupted browsing for Windows and Linux users when there is a crash in the Adobe Flash, Apple Quicktime or Microsoft Silverlight plugins. When users get crashes with the plugin, they can still be able to reload the page to restart the plugin and try again. It means your browser will not automatically close.
Firefox 3.6.4 also fixes some issues found in previous versions of Firefox 3.6.
Pay your attention this is still beta (pre-release) not final version. you may encounter compatibility problems with some websites and add-ons. Use this version just for testing purpose only not for browsing activiry. Anduse with your own risk.