I just upgraded to windows 8 from windows 7. Visual studio 2010 broke down completely. Oh well. I removed vs2012 and installed visual studio 2012, where the pain starts. I h
For me, this happened when I installed mysql on my machine, and it added an extra connection string to my machine config. However, since I was using a separate file for configSource, it resulted my machine config to become corrupted.
Moving the new config key to my config source from the 32bit machine config solved the issue.