CompileXaml" task could not be instantiated

I created a a silverlight application. While creating i got an error box saying "The security state of an AppDomain was modified by an AppDomainManager configured with the NoSecurityChanges flag". I Ignored and created the app. When building the application i get error  saying "Error1The "CompileXaml" task could not be instantiated from "C:\Program Files\MSBuild\Microsoft\Silverlight\v4.0\Microsoft.Silverlight.Build.Tasks.dll". The security state of an AppDomain was modified by an AppDomainManager configured with the NoSecurityChanges flag." and "Error2The "CompileXaml" task has been declared or used incorrectly, or failed during construction. Check the spelling of the task name and the assembly name.". I surfed a bit and tried all the related options such as setting NetFx40_LegacySecurityPolicy enabled="true" in devenv.exe.config . Nothing worked out. Please someone help regarding this.