I'm not sure if this is releated tothe FriendlyURLs or not, but accessing the Host -> Settings I get this error:

Suggestions?

Error: Host Settings is currently unavailable.
DotNetNuke.Services.Exceptions.ModuleLoadException: D:\InetPub\DotNetNuke\admin\Host\FriendlyUrls.ascx.vb(229): error BC30456: 'SaveConfig' is not a member of 'DotNetNuke.HttpModules.Config.RewriterConfiguration'. ---> System.Exception: D:\InetPub\DotNetNuke\admin\Host\FriendlyUrls.ascx.vb(229): error BC30456: 'SaveConfig' is not a member of 'DotNetNuke.HttpModules.Config.RewriterConfiguration'. ---> System.Web.HttpCompileException: D:\InetPub\DotNetNuke\admin\Host\FriendlyUrls.ascx.vb(229): error BC30456: 'SaveConfig' is not a member of 'DotNetNuke.HttpModules.Config.RewriterConfiguration'. at System.Web.Compilation.BuildManager.PostProcessFoundBuildResult(BuildResult result, Boolean keyFromVPP, VirtualPath virtualPath) at System.Web.Compilation.BuildManager.GetBuildResultFromCacheInternal(String cacheKey, Boolean keyFromVPP, VirtualPath virtualPath, Int64 hashCode) at System.Web.Compilation.BuildManager.GetVPathBuildResultFromCacheInternal(VirtualPath virtualPath) at System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.UI.BaseTemplateParser.GetReferencedType(VirtualPath virtualPath, Boolean allowNoCompile) at System.Web.UI.BaseTemplateParser.GetUserControlType(VirtualPath virtualPath) at System.Web.UI.MainTagNameToTypeMapper.ProcessUserControlRegistration(UserControlRegisterEntry ucRegisterEntry) at System.Web.UI.BaseTemplateParser.ProcessDirective(String directiveName, IDictionary directive) at System.Web.UI.TemplateControlParser.ProcessDirective(String directiveName, IDictionary directive) at System.Web.UI.TemplateParser.ParseStringInternal(String text, Encoding fileEncoding) --- End of inner exception stack trace --- at System.Web.UI.TemplateParser.ProcessException(Exception ex) at System.Web.UI.TemplateParser.ParseStringInternal(String text, Encoding fileEncoding) at System.Web.UI.TemplateParser.ParseString(String text, VirtualPath virtualPath, Encoding fileEncoding) at System.Web.UI.TemplateParser.ParseFile(String physicalPath, VirtualPath virtualPath) at System.Web.UI.TemplateParser.ParseInternal() at System.Web.UI.TemplateParser.Parse() at System.Web.Compilation.BaseTemplateBuildProvider.get_CodeCompilerType() at System.Web.Compilation.BuildProvider.GetCompilerTypeFromBuildProvider(BuildProvider buildProvider) at System.Web.Compilation.BuildProvidersCompiler.ProcessBuildProviders() at System.Web.Compilation.BuildProvidersCompiler.PerformBuild() at System.Web.Compilation.BuildManager.CompileWebFile(VirtualPath virtualPath) at System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.UI.TemplateControl.LoadControl(VirtualPath virtualPath) at System.Web.UI.TemplateControl.LoadControl(String virtualPath) at DotNetNuke.UI.Skins.Skin.InjectModule(Control objPane, ModuleInfo objModule, PortalSettings PortalSettings) --- End of inner exception stack trace ---

I had some more time to  play with this, If I restore the orginal DotNetNuke.HttpModules.UrlRewrite.dll,  & the orginal Web.Config settings, the problem goes away. It does appear to be related to this Feature.