inapplications 
Windows Installer allows software developers to configure installation packages for easy setup. But your computer gives you an error message that Windows cannot open an installation package, or there’s another problem with Windows Installer, you can attempt to repair it using one of several methods.
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Its best to let your Mac go into sleep mode when you’re not using it, so it doesn’t generate too much heat or use too much power. But if you do want to disable sleep mode, it’s an option in OS X System Preferences.
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