This probably has to do with the way you reference your projects. If you are referencing them as DLLs instead of projects, after a clean you will get missing reference/undef. Symbols errors until you build them.
I can't be sure that this is your case, but I have seen this be done before when you have multiple projects in your solution that have references to one another. When doing so, your build order must be correct. If this is the case, right-click on your solution in the Solution Explorer and select "Project Dependencies..." and make sure this looks right.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.