Have you ever seen an error trace like the below in the Sitecore log?
System.NotSupportedException: Unknown request type: PROPFINDContinue reading “Error with PROFIND Requests”
at Sitecore.Mvc.Helpers.WebHelper.GetRequestType (HttpContextBase httpContext)
at Sitecore.Mvc.Pipelines.Request.RequestBegin.ExecuteFormHandler.Process(RequestBeginArgs args)
...