As part of the out-with-the-old-in-with-the-new methodology enforced by the product manager we are setting up the server to have as little legacy and unnecessary crap as possible.
Since our solution compiles inVS 2012 we chose not to install VS2010 since we thought it was not required any longer.
We were wrong. Although our solution does indeed compile in VS2012, many of the projects are set to work with the v110 toolset (i.e. VS2010). This caused an issue because apparently because we didn't have VS2010 installed the project's path Macro for $(WindowsSDKDir) was empty. Empty you ask? What is empty?
This is empty (picture edited for demonstration, field is no longer really empty):
|Empty $(WindowsSdkDir) value|
This field remained empty even though the environment variable existed, was defined and several attempts were made to redefine it or re-install/re-configure the Windows SDK.
The solution was to also install VS2010. Apparently since the toolset for the project is set to use VS2010 and it wasn't installed VS chose to hides specific environment variables...