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.
Recently I found this sometimes occurs when I launch several solutions at once (i.e. I have 1 or more Visual Studio instances loading a solution at the same time). I also have ReSharper, SQL Prompt, VSCommands and TFS Power Tools installed which I'm sure contribute to some degree.
UPDATE:
This fix should work for all versions of Visual Studio, however you will need to execute the command in the directory appropriate to your version. For example with Visual Studio 2015 the path would be:
"C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE\devenv.exe" /setup