exceptions on build

Why do I get this exception and how do I fix it?
This occurs on build.
A first chance exception of type 'System.UnauthorizedAccessException' occurred in mscorlib.dll
A first chance exception of type 'System.IO.FileNotFoundException' occurred in mscorlib.dll A first chance exception of type 'System.IO.FileNotFoundException' occurred in mscorlib.dll A first chance exception of type 'System.IO.FileNotFoundException' occurred in mscorlib.dll A first chance exception of type 'System.IO.FileNotFoundException' occurred in mscorlib.dll A first chance exception of type 'System.IO.FileNotFoundException' occurred in mscorlib.dll A first chance exception of type 'System.IO.FileNotFoundException' occurred in mscorlib.dll A first chance exception of type 'System.IO.FileNotFoundException' occurred in mscorlib.dll A first chance exception of type 'System.IO.FileNotFoundException' occurred in mscorlib.dll A first chance exception of t ...