在wp7上运行项目时TargetInvocationException

我有一个大型的wp7专案，在wp7上运作良好。在过去的几个星期中，我使用wp8设备进行调试（项目仍适用于wp7），一切都很好。

现在，我开始在wp7设备上对其进行测试，这使我望而却步

System.Windows.Application.LoadComponent(this, new System.Uri("/MyApp;component/App.xaml", System.UriKind.Relative));

这个例外

System.Reflection.TargetInvocationException occurred
  Message=TargetInvocationException
  StackTrace:
       at System.Reflection.RuntimeConstructorInfo.InternalInvoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, StackCrawlMark& stackMark)
       at System.Reflection.ConstructorInfo.Invoke(Object[] parameters)
       at MS.Internal.TypeProxy.<>c__DisplayClass30.<GetCreateObjectDelegate>b__2a()
       at MS.Internal.TypeProxy.CreateInstance(UInt32 customTypeId)
       at MS.Internal.XamlManagedRuntimeRPInvokes.CreateInstance(XamlTypeToken inXamlType, XamlQualifiedObject& newObject)
       at MS.Internal.XcpImports.Application_LoadComponentNative(IntPtr pContext, IntPtr pComponent, UInt32 cUriStringLength, String uriString, UInt32 cXamlStrLength, Byte* pXamlStr, UInt32 cAssemblyStrLength, String assemblyStr)
       at MS.Internal.XcpImports.Application_LoadComponent(IManagedPeerBase componentAsDO, String resourceLocator, UnmanagedMemoryStream stream, UInt32 numBytesToRead, String assemblyString)
       at System.Windows.Application.LoadComponent(Object component, Uri resourceLocator)
       at MyApp.App.InitializeComponent()
       at MyApp.App..ctor()
       at System.Reflection.RuntimeConstructorInfo.InternalInvoke(RuntimeConstructorInfo rtci, BindingFlags invokeAttr, Binder binder, Object parameters, CultureInfo culture, Boolean isBinderDefault, Assembly caller, Boolean verifyAccess, StackCrawlMark& stackMark)
       at System.Reflection.RuntimeConstructorInfo.InternalInvoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, StackCrawlMark& stackMark)
       at System.Reflection.ConstructorInfo.Invoke(Object[] parameters)
       at MS.Internal.TypeProxy.<>c__DisplayClass30.<GetCreateObjectDelegate>b__2a()
       at MS.Internal.TypeProxy.CreateInstance(UInt32 customTypeId)
       at MS.Internal.FrameworkCallbacks.CreateKnownObject(IntPtr nativeRootPeer, UInt32 customTypeId, String initializationString, IntPtr& nativePeer, UInt32 isCreatedByParser)
       at MS.Internal.FrameworkCallbacks.CreateUnknownObject(String assemblyName, String typeName, IntPtr nativeRootPeer, String initializationString, UInt32& customTypeId, UInt32& coreTypeId, UInt32& typeFlags, IntPtr& nativePeer)
  InnerException: System.MissingMethodException
       Message=Could not load type 'System.Func`2' from assembly 'mscorlib, Version=3.7.0.0, Culture=neutral, PublicKeyToken=969DB8053D3322AC'.

我改变了很多东西，所以我不知道在哪里看。

有什么可能是原因的建议吗？那是System.Func'2什么？

编辑：只是为了再次澄清一下：项目始终针对wp7。当前是：

EDIT2：输出为：

'TaskHost.exe' (Managed): Loaded 'System.Device.dll' 
'TaskHost.exe' (Managed): Loaded 'Cimbalino.Phone.Toolkit.Background.dll'
'TaskHost.exe' (Managed): Loaded 'Cimbalino.Phone.Toolkit.dll'
'TaskHost.exe' (Managed): Loaded 'GalaSoft.MvvmLight.Extras.WP71.dll'
'TaskHost.exe' (Managed): Loaded 'System.Runtime.Serialization.dll'

也许可以帮上忙吗？wp7上的Serialization.dll出现问题吗？

EDIT3：我的系统配置：Windows 8.1 Pro，MSVS Pro 2012 Update 4。