Error: "Unable to cast COM object of type 'Word.ApplicationClass' to interface type 'Word._Application [...] Exception from HRESULT: 0x80029C4A (TYPE_E_CANTLOADLIBRARY)." when attempting to send e-mail

Symptom: I am attempting to write an e-mail in Act! with Microsoft Outlook configured as my default email client and I receive the Error: "Unable to cast COM object of type 'Microsoft.Office.Interop.Outlook.ApplicationClass' to interface type 'Microsoft.Office.Interop.Outlook._Application'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{00063001-0000-0000-C000-000000000046}' failed due to the following error: Error loading type library/DLL. (Exception from HRESULT: 0x80029C4A (TYPE_E_CANTLOADLIBRARY))."

Product Details:
Product Family: Act! 
Product: Act! Premium
Version: v18

Environment: 
OS: Windows 10
Third Party: Microsoft Outlook

Cause:
This can occur if there was a trial version of Microsoft Office 2016 installed on the computer, but you downgraded to a previous version of Office. It has also been known to be caused by a fault in the Microsoft Office installation which can be fixed with an automatic repair.

Solution:

This issue can be resolved by deleting an invalid registry key left over from the higher version of Office. Follow the steps below that pertain to your scenario:

Important Note: It is strongly recommended that you create a backup of your Windows registry before proceeding with the steps below. For information on creating registry backups, refer to the following Microsoft documentation:

How to back up and restore the registry in Windows


If you downgraded from Office 2010 to Office 2007

1. Close Act! and all Office applications (Outlook, Word, Excel®).
2. Click your Windows® Start button, either click Run or go to the Search box on the Start Menu, and type regedit. The Windows registry editor opens.
3. Navigate to the following key: HKEY_CLASSES_ROOT\TypeLib\{00062FFF-0000-0000-C000-000000000046}\9.4
4. Delete the 9.4 key.
5. Close the registry editor.
6. Reopen Outlook, reopen Act! then click on a contact's email address to test.

If you downgraded from Office 2013 to Office 2010 or 2007

1. Close Act! and all Office applications (Outlook, Word, Excel®).
2. Click your Windows Start button, either click Run or go to the Search box on the Start Menu, and type regedit. The Windows registry editor opens.
3. Navigate to the following key: HKEY_CLASSES_ROOT\TypeLib\{00062FFF-0000-0000-C000-000000000046}\9.5
4. Delete the 9.5 key.
5. Close the registry editor.
6. Reopen Outlook, reopen Act! then click on a contact's email address to test.

If you downgraded from Office 2016 to Office 2013, 2010, or 2007

1. Close Act! and all Office applications (Outlook, Word, Excel®).
2. Click your Windows Start button, either click Run or go to the Search box on the Start Menu, and type regedit. The Windows registry editor opens.
3. Navigate to the following key: HKEY_CLASSES_ROOT\TypeLib\{00062FFF-0000-0000-C000-000000000046}\9.6
4. Delete the 9.6 key.
5. Close the registry editor.
6. Reopen Outlook, reopen Act! then click on a contact's email address to test.

Repairing Microsoft Office

If the above steps are unsuccessful, you can attempt to perform an automatic repair of Microsoft Office. To do this, follow the steps below:

1. Make sure all Office programs are currently closed.
2. Click the Start menu and type in Control Panel then press return.
3. When using the L:arege or small icons views, click Programs and Features.
4. Locate Microsoft Office in the list.
5. Right click Microsoft Office, then click Change.
6. Choose the option to Repair.