Class not registered error when creating Excel workbook in C#

Question

When I try to access an Excel spreadsheet using the following code I get a \"Library not registered\' error when defining the workbook object wrkbuk using C# from Visual Studio

Answer 1

I will confirm @stuzor 's answer on two machines I've encountered.

Background:

Windows7 64 bit
Office 2010 (32bit) 
Lync 2013 

HKEY_CLASSES_ROOT\TypeLib\ , searched for "Office.Interop.Excel". Found the barely existent "1.8" folder. Upon deletion, the function in an old VB.net app began working immediately.