When inserting a quiz I receive an error message stating "This app could not be started."

IE needs to be running with protected mode enabled in the Internet Zone for the quizzes, videos and apps to work in PowerPoint.

For security reasons, when PowerPoint launches Internet Explorer to host the Office Mix quizzes, videos and apps it does so in a low privilege mode. This is to provide the maximum amount of security to you as a user. If protected mode is also disabled then PowerPoint does not have the access rights required to access IE and so the apps fail to launch If Protected Mode is disabled for the internet zone, PowerPoint cannot initiate a low integrity IE session and so the apps fail to launch. 

To fix this follow the steps at the link below:
http://support.microsoft.com/kb/2761180

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