Revit 2015 Extensions + Key not valid for use in Specified State

Today's featured Knowledge Article is brought to you by the tenacious troubleshooting guru Jeremy Hanson.  If you are installing Revit Extensions for Autodesk Revit 2014 and you will get the following error:

 Red X:  Key not valid for use in Specified State

Please check out the following Knowledge Article to solve your problem.

http://knowledge.autodesk.com/search-result/caas/sfdcarticles/sfdcarticles/installation-error-key-not-valid-for-use-in-specified-state.html

Epilogue

This key not valid error can apply any software product.  There have been reports the same error and solution when installing Microsoft Visual C++ and Adobe Acrobat Reader.