The Not-So-ReadOnlyCollectionhttp://msmvps.com/blogs/cmullins/archive/2007/03/18/the-not-so-readonlycollection.aspxThe ReadOnlyCollection class is in no way makes the guarantee that your collection is Read Only. Don't make the assumption that you can treat it as Read Only. Read More...enCommunityServer 2008.5 SP2 (Build: 40407.4157)