I'm sorry about the issue. Please try each of the followings until it works:
- Open Finder -> Applications -> Utilities -> Activity Monitor, then if you see any firefox item there, then select it and quit it.
- Click on the Apple logo / menu at the top, then click on the Restart option, and confirm.
- Press at the same time Command–Control–Power button to restart the computer and check.
- Press and hold the Power on/off button on the computer for about 10 (or about 30) seconds, then turn it back on and check.
Please reply at the box below to continue troubleshooting. Thank you.
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