A problematic extension can cause the problem, which can be resolved by disabling or uninstalling the extension. For information on diagnosing and fixing problems caused by faulty extensions, see the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article.. This has become an extremely annoying issue, it happens no matter what i m doing on the web, even when reading my web based email and . Firefox updated to latest and now not respond and hangs. Once press X to close and check task manager firefox is in the background list using . If you ve been beset currently by the trouble that Mozilla Firefox is not responding or working on your Windows or Mac. Here are FIVE feasible .