The latest release of the Flash Player plugin, version 11.3, is causing frequent crashes in Firefox 13 on Windows. The problem seems to be related to the recently introduced Protection Mode, which is supposed to make the plugin run in a sandbox to isolate it from the rest of the system. The number of users experiencing this problem is now so large that Mozilla and Adobe are both offering differing solutions for a fix.
Many of the crashes appear to be the result of interactions between Flash Player and other plugins, particularly plugins which offer the ability to record Flash video streams. Mozilla specifically mentions a Firefox extension called RealPlayer Browser Record and recommends deactivating this plugin. The Firefox developers have also added this plugin to its blacklist which comprises add-ons known to be insecure or unstable. Firefox automatically disables extensions on this list, but allows users to reactivate them manually.
A further option for remedying the problem is to deactivate Protected Mode. Under Windows 7 or Vista, this requires the addition of the line ProtectedMode=0 to the configuration file mms.cfg. Since Protected Mode is not used under Windows XP, this step is not necessary on that platform.
<%windir%\syswow64\macromed\flash itxtharvested="0" itxtnodeid="301">%windir%\syswow64\macromed\flash>