Error: "Object reference not set to an instance of an object" when importing from Microsoft Excel

Symptom: Error: "Object reference not set to an instance of an object" when importing from Excel

Product Details: 
Product Family: Act!
Product: Act! Premium
Version: v18.0

Environment:
OS: Windows 10
Third Party: Microsoft Office 2010

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Cause:
This can occur due to a Windows permissions error.

Solution: 

1. Close Act!
   
2. Right-click the Act! icon on your desktop and choose Run As Administrator
3. Attempt to import from Excel to test