This is strange. I use MSVC2012 Express edition with Windows 8 myself and I do not have these problems.
I'll see if I can figure out what might be going on.
Well, when I use the pre-processor definition AS_NO_THREADS, I don't get these errors anymore, but to my understanding, that removes the multi-threading capabilities of AngelScript.
the cpp's are not included in the project itself? (in my experience,
Visual Studio does not search among folders to look for files. you have
to tell it that there are "existing items". Try to drag and drop those
files from the explorer maybe? I dunno. never happened to me before.
That shouldn't be the problem though, as the methods that are 'not found' are in the headers provided in the Win32 API (according to the MSDN documentation at least).