解决方案

Option 1 - Perform a clean re-construction of Tableau Prep Repository folder

1. In Task Manager, make sure that Tableau Prep Builder process is not running
2. Rename the My Tableau Prep Repository folder (located by default at C:\Users\<username>\Documents\My Tableau Prep Repository) to My Tableau Prep Repository_Backup.
3. Start Tableau Prep Builder

Option 2 - Repair the Tableau Prep Builder installation

Option 3 - Run Tableau Prep Builder as administrator 

Option 4 - Perform a clean re-installation of Tableau Prep Builder

1. Download a new copy of the installer from the Product Downloads and Release Notes page.
2. Uninstall Tableau Prep Builder. 
3. Delete the following folder: C:\Program Files\Tableau\Tableau Prep Builder <version>
4. Rename the My Tableau Prep Repository folder (located by default at C:\Users\<username>\Documents\My Tableau Prep Repository) to My Tableau Prep Repository_Backup.
5. Reinstall Tableau Prep Builder using the newly downloaded installer.