To fix the issue simply run the below command in an elevated command prompt as detailed here.
"C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\IDE\devenv.exe" /setup
My understanding is this command forces the recreation (what Microsoft refers to as "merging") of current VS settings into what is apparently a corrupt settings cache. On the surface, this is similar to deleting the directory path C:\Users\username\AppData\Local\Microsoft\VisualStudio\version and allowing visual studio to recreate it at launch.
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