If you get this error while viewing a webpage, it means a plugin has crashed. You can send a crash report to Mozilla by clicking on Send crash report.
A plugin is a piece of software that displays internet content that Firefox is not designed to display. These usually include video, audio, online games and presentations that are made in patented formats. Plugins are created and distributed by the companies that make those patented formats. Some common plugins are Adobe Flash, Apple QuickTime, and Microsoft Silverlight.
A crash happens when a piece of software quits working. Plugins sometimes crash and cause Firefox to crash along with it. On Windows and Linux, Firefox 3.6.4 and above will load some plugins separately from Firefox, allowing Firefox to stay open if the plugin crashes.
When a crash report is sent to Mozilla, Firefox developers use the information to make future versions of Firefox crash less frequently. Crash reports do not include any personally identifying information. They only include technical information, such as:
For more information about Firefox crash reports, see Firefox crashes - Troubleshoot, prevent and get help fixing crashes.
Many problems with plugins can be solved by updating to the latest version of the plugin. To check if any of your installed plugins are out of date, visit Mozilla's Plugin Check & Updates page.
The name of the plugin that crashed can be found in the error message.
Breakpoints can trigger Firefox's hang protection. You can disable hang protection by setting dom.ipc.plugins.timeoutSecs to -1. See Disable Hang Protection for details.