When trying to install Office Timeline, you keep getting prompted to close PowerPoint even though you know you’ve already closed it.
The Office Timeline add-in requires Microsoft PowerPoint to be closed during the installation.
In some cases, even if PowerPoint looks like it’s closed, there may be a residual process still running in the background that you need to manually end as described below.
Open Task Manager by pressing Ctrl+Alt+Delete
Locate Microsoft PowerPoint in the Processes tab
Right-click and select End Task