Failed to map the path '/'

Error : Failed to map the path '/'
This is a ridiculous error that is generated depending on the .Net framework used. When you are using Server.MapPath in .net framework 3.5 be sure to use  Server.MapPath("..") and in .net framework 2.0 you should use Server.MapPath("~/") to get the root. Well bad news is this is not the case always. If one does not work try the other. Yes, do trial and error!