The template "crashsig" does not exist or has no approved revision. Flash_EnforceLocalSecurity, CFReadStreamGetStatus or Flash Player@0x91bd0
Some versions of Flash on Mac OS X will cause Firefox to crash on pages using the Flash plugin. Adobe has released an updated version of Flash that should fix this.
Read the Flash Plugin - Keep it up to date and troubleshoot problems article for more information about the Flash player plugin or the Firefox crashes - Troubleshoot, prevent and get help fixing crashes article for more help with crashing in Firefox.