Porque da Error al editar el parametro de aplicacion VacacionSPCalculoDuracion?

Con solo entrar a ese parametro y darle Guardar da este error, se quito la descripcion, se cambio la unidad, se hizo la prueba con otros Alfanumericos y solo con este da error. Que podra ser? Se probo en version 1.8.3.1 y 1.8.4.4 da el mismo error.

System.InvalidOperationException: An object with a key that matches the key of the supplied object could not be found in the ObjectStateManager. Verify that the key values of the supplied object match the key values of the object to which changes must be applied. at System.Data.Objects.ObjectContext.ApplyCurrentValuesTEntity at Aseinfo.Infrastructure.Base.Entity.GenericEntityRepository.UpdateWithoutSavingChangesT in c:VH4InfrastructureBaseEntityGenericEntityRepository.cs:line 183 at Aseinfo.Infrastructure.Base.Entity.EntityServiceBase2.DoUpdate(T entity, Boolean saveChanges) in c:\VH4\Infrastructure\Base\Entity\EntityServiceBase.cs:line 921 at Aseinfo.VH4.General.Controllers.ParametroAplicacionController.SaveParametroAplicacion(ParametroAplicacion entity, Boolean inserting) at Aseinfo.VH4.General.Controllers.ParametroAplicacionController.Edit(ParametroAplicacion entity) at lambda_method(Closure , ControllerBase , Object[] ) at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary2 parameters) at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary2 parameters) at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass15.<InvokeActionMethodWithFilters>b__12() at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func1 continuation) at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func1 continuation) at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func1 continuation) at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList1 filters, ActionDescriptor actionDescriptor, IDictionary2 parameters) at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)