Visual Studio can't 'see' my included header files

Question

I created an empty \'Demo\' project in Visual Studio 2008 and added some existing projects to my solution. Included \"MyHeader.h\" (other project\'s header) in main.cpp file

Answer 1

This happened to me just now, after shutting down and restarting the computer. Eventually I realised that the architecture had somehow been changed to ARM from x64.