I took a day off, downloaded and reinstaled the hole VS pack and that warning disapeared.
I got others thou, but after googling around they seem to be of the "ignore it" type.
"WCF client proxy auto generation failed. Unable to cast transparent proxy to type 'Microsoft.VisualStudio.ServiceModel.ClientCodeGeneration.CrossAppDomainHelper'."
"The element 'Target' in namespace 'http://schemas.microsoft.com/developer/msbuild/2003' has invalid child element 'GenerateWcfClientFilesTask' in namespace 'http://schemas.microsoft.com/developer/msbuild/2003'. List of possible elements expected: 'Task, AL, AspNetCompiler, AssignCulture, AssignProjectConfiguration, AssignTargetPath, AxImp, CallTarget, CombinePath, ConvertToAbsolutePath, Copy, CreateCSharpManifestResourceName, CreateItem, CreateProperty, CreateVisualBasicManifestResourceName, Csc, Delete, Error, Exec, FindAppConfigFile, FindInList, FindUnderPath, FormatUrl, FormatVersion, GenerateApplicationManifest, GenerateBootstrapper, GenerateDeploymentManifest, GenerateResource, GenerateTrustInfo, GetAssemblyIdentity, GetFrameworkPath, GetFrameworkSdkPath, GetReferenceAssemblyPaths, LC, MakeDir, Message, Move, MSBuild, ReadLinesFromFile, RegisterAssembly, RemoveDir, RemoveDuplicates, RequiresFramework35SP1Assembly, ResolveAssemblyReference, ResolveComReference, ResolveKeySource, ResolveManifestFiles, ResolveNativeReference, ResolveNonMSBuildProjectOutput, SGen, SignFile, TlbImp, Touch, UnregisterAssembly, UpdateManifest, Vbc, VCBuild, Warning, WriteCodeFragment, WriteLinesToFile, XslTransformation, CodeAnalysis, CL, Link, BSCMake, CPPClean, Get.... C:\Program Files\MSBuild\Microsoft\Silverlight\v4.0\Microsoft.VisualStudio.ServiceModel.targets"
Are they really to be ignored?