On June 22Mozillalaunch the Firefox version 3.6.4 with crash protection. This mean if a plug in crash, Firefox not, this is a great improvement to prevent the data, game score or whatever you are doing.
If you want to update, just do it with your browser update tool (top menu->help->update) or download the full installer from Mozilla dot com.
At this time Firefox offers crash protection for Adobe Flash, Apple Quicktime and Microsoft Silverlight on Windows and Linux computers. Support for other plugins and operating systems will become available in a future Firefox release.
You can check too the plug-in support before download this update, sometimes when you make an update, some plug-ins stop working, avoid this checking before the compatibility, to verify this, follow this link.
Source: Mozilla Blog