Error: "The application has encountered an error and has been shut down" is displayed when I open Act!

Symptom: Error: "The application has encountered an error and has been shut down" is displayed when I open Act! but when I click OK Act! remains open

Product Details:
Product Family: Act!
Product: Act! Premium
Version: v17.2

Environment:
OS: Windows 7

---

Cause: This can be caused due to a 3rd party add-on.

Solution: You can identify the add-on causing the issue by following the steps below:

1. In Act! go to Tools > Design Layout > Contact
   
   
   Important: This displays an unhandled exception error as detailed below and will also display the add-on name, if an error is not displayed to can continue to follow the steps and disable all add-ons:
   
   Error: "Error picked up by [YOUR-ADD-ON-NAME] add-on:
    
   Global Exception
   System.IO.FileNotFoundException: Could not load file or assembly 'Exponenciel.ActAppUI, Version=12.0.0.1, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified.
   File name: 'Exponenciel.ActAppUI, Version=12.0.0.1, Culture=neutral, PublicKeyToken=null'"
   
   
2. Go to Tools > Manage Add-Ons... 
   
3. Identify the add-on referenced in the error message and untick it, or if this is unknown disable all add-ons
   
4. Click Apply, a prompt advising to restart Act!, click OK
   
5. Click Close to exit Manage add-ons and restart Act!
   
6. Test issue