C#を用いたUnityでのエラー

UnityでBuildを行ったところ以下のような３つのエラーがでて困っています．

ArgumentException: The Assembly System.ComponentModel.Composition is referenced by System.Runtime ('Assets/System.Runtime.dll'). But the dll is not allowed to be included or could not be found.
UnityEditor.AssemblyHelper.AddReferencedAssembliesRecurse (System.String assemblyPath, System.Collections.Generic.List`1 alreadyFoundAssemblies, System.String[] allAssemblyPaths, System.String[] foldersToSearch, System.Collections.Generic.Dictionary`2 cache, BuildTarget target) (at C:/buildslave/unity/build/Editor/Mono/AssemblyHelper.cs:154)
UnityEditor.AssemblyHelper.FindAssembliesReferencedBy (System.String[] paths, System.String[] foldersToSearch, BuildTarget target) (at C:/buildslave/unity/build/Editor/Mono/AssemblyHelper.cs:194)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

Build completed with a result of 'Failed'
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

UnityEditor.BuildPlayerWindow+BuildMethodException: 3 errors
  at UnityEditor.BuildPlayerWindow+DefaultBuildMethods.BuildPlayer (BuildPlayerOptions options) [0x0021f] in C:\buildslave\unity\build\Editor\Mono\BuildPlayerWindowBuildMethods.cs:182 
  at UnityEditor.BuildPlayerWindow.CallBuildMethods (Boolean askForBuildLocation, BuildOptions defaultBuildOptions) [0x00065] in C:\buildslave\unity\build\Editor\Mono\BuildPlayerWindowBuildMethods.cs:89 
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

Unityは最新バージョンに更新し，PalyerSettingsのApi Compatibility Levelは.NET 2.0にしました．ビルド先のフォルダもデスクトップにしましたが結果は同じでした．

言語はC#，Windowsで作成しています．
Androidとかではなく，Windowsで動く.exeソフトです．
よろしくお願いします．