No matter what I have tried, I cannot re-order the nodes in my Umbraco back-end.

It used to work, but now it doesn't. It just goes off and says it working but nothing happens.

in Fiddler, I see a lot of these responses:

{"Message":"There was an error processing the request.","StackTrace":"","ExceptionType":""}

and seeing this error in the log:

Error adding to SiteMapProvider: System.InvalidOperationException: Multiple nodes with the same URL '/' were found. XmlSiteMapProvider requires that sitemap nodes have unique URLs. at System.Web.StaticSiteMapProvider.AddNode(SiteMapNode node, SiteMapNode parentNode) at umbraco.presentation.nodeFactory.UmbracoSiteMapProvider.loadNodes(String parentId, SiteMapNode parentNode)

how do I find which other node has the root '/' url?