Mystery of repeated links created in navigation crashes entire site!

Hi

I have publishing switched on. I think a user has created a page not checked it in  and manually added this to the quick navigation, this is a theory!

The whole of sharePoint  has become unresponsive so i cannot check in Site Settings. This happened about a month back and I was able to delete the offending link within navigation settings, now i cant access site settings at all.

I've checked the ULS and have the following error:

i can access the sites through SPD but cannot see anything wrong. Is there any other way of isolating issue?

PortalSiteMapProvider was unable to fetch children for node
 at URL: /HR, message: An unexpected error occured while manipulating the navigational structure of this Web., stack trace:   
 at Microsoft.SharePoint.SPGlobal.HandleComException(COMException comEx)    
 at Microsoft.SharePoint.Library.SPRequest.UpdateNavigationNode(String bstrUrl, Int32 lNodeId, DateTime dateParented, String bstrName, String bstrNodeUrl, Object& pvarProperties, String& pbstrDateModified)    
 at Microsoft.SharePoint.Navigation.SPNavigationNode.Update()    
 at Microsoft.SharePoint.Publishing.Navigation.SPNavigationSiteMapNode.UpdateSPNavigationNode(SPNavigationNode node, SPNavigationNode previous, String name, String url, String description, String target, String audience, Boolean forceCreate)    

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