If you want to keep Widgets enabled but clean it up a bit, open the Widgets menu, click the Settings gear in the top-right ...
When an application doesn't respond, it's usually accompanied by it gobbling up system resources. Should that application consume all your remaining CPU or RAM, your system could become unresponsive, ...
Inevitably, just like any laptop, your MacBook will freeze up on you. Here are some ways to use keyboard shortcuts to shut ...