When attempting to install the Classroom Presentation Tool you may receive an error message: 

Sorry, an error has occurred. 

The application could not be installed because the installer file is damaged. Try obtaining a new installer file from the application author.

You can resolve this issue by doing the following:

  1. Quit the installer. 
  2. Open the date and time preferences on your computer. 
  3. Change the date on your computer to prior to October 30, 2017. 
  4. Run the installer again. 
  5. When the installer completes launch the application. 
  6. When you have ensured that the application launches as expected, update your computer to today's date and time.