The installation package could not be opened

On some computers, when launching the Power-user.exe setup, the following error will appear, stating "This installation package could not be opened. Verify that the package exists and that you can access it , or contact the application vendor to verify that this is a valid Windows Installer package"

This is an error coming from Windows (not from Power-user). It can usually be solved quite easily.

Step 1: 

• Delete the file you have already downloaded.
• Download the file again, from a different browser. 
• Place the .exe on a local drive (Windows will be more suspicious if the package is on a network drive).
• Try again to install the setup.

• Go to the Windows "Start" menu and click on "Control Panel".
• Go to "Administrative Tools".
• Click on "Services" and scroll to "Windows Installer".
• Double click to bring up the service.
• Check to see if the startup type is set to "Manual".
• Service status is usually stopped. Try and start the Windows Installer service.
• Now try to install the setup.

• Click the Windows "Start" menu, and type "cmd".
• Then right-click and select, "Run as Administrator".
• At the command prompt, type:
  • Type msiexec.exe /unregister, and then press ENTER.
  • Type msiexec.exe /regserver, and then press ENTER.
• Now try to install the setup.

• Click the Windows "Start" menu
• Type: "CMD", and from the results, right-click "CMD"
• Click "Run as Administrator".
• At the Command Prompt, type: sfc /scannow
• This will check for any integrity violations and fix any corrupted operating system files.
• Restart your system.
• Try again to install the setup.

• If applicable, deactivate Cisco Secure Endpoints from the Task Manager
• Try again to install the setup