Error while installing the Excel Add-in or Outlook Add-in

If while installing Clarizen's Excel Add-in or Outlook Add-in, you get the following error 

That error can be corrected with the following steps:

1) Navigate to the directory where "VSTOInstaller.exe.config" resides, in this case C:\Program Files(x86)\Common Files\Microsoft Shared\VSTO\10.0

2) Rename VSTOInstaller.exe.config to VSTOInstaller.exe.config.old

3) Re-run the add-in installer