Mozilla released Firefox 3.6.4 Beta (Build 5) which fixed several security and stability issues found in build 4 of Firefox 3.6.4 Beta , if you are using Firefox 3.6.4 Beta it is recommended to update to latest version of Firefox.

Firefox 3.6.4 provides uninterrupted browsing  for Windows,Mac and Linux users even though there is crash of plugins like Flash player, Quick time and Microsoft Silverlight plugins.

If a Plug-in crashes it will not affect rest of the Firefox, you can still able reload the page to restart the plugin.

For more details read Firefox 3.6.4 Beta (Build 5 ) release notes.