hey,

i'm not sure what has happened during the last couple of hours but suddenly my home node and its level below have become corrupt - when i click on them in the CMS i get the following:

- Home (error)
-- Landing Page (error)
--- Generic Page (working)
-- Second Landing Page (error)
--- Generic Page (working)
-- Generic Page (error)

An item with the same key has already been added.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 
Exception Details: System.ArgumentException: An item with the same key has already been added. 
Stack Trace: 
at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)
   at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
   at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
   at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector)
   at Umbraco.Core.Persistence.Repositories.VersionableRepositoryBase`2.GetPropertyCollection(Int32 id, Guid versionId, IContentTypeComposition contentType, DateTime createDate, DateTime updateDate)
   at Umbraco.Core.Persistence.Repositories.ContentRepository.CreateContentFromDto(DocumentDto dto, Guid versionId)
   at Umbraco.Core.Persistence.Repositories.ContentRepository.PerformGet(Int32 id)
   at Umbraco.Core.Persistence.Repositories.RepositoryBase`2.Get(TId id)
   at Umbraco.Core.Services.ContentService.GetById(Int32 id)
   at Umbraco.Web.Editors.ContentController.CheckPermissions(IDictionary`2 storage, IUser user, IUserService userService, IContentService contentService, Int32 nodeId, Char[] permissionsToCheck, IContent contentItem)
   at Umbraco.Web.WebApi.Filters.EnsureUserPermissionForContentAttribute.OnActionExecuting(HttpActionContext actionContext)
   at System.Web.Http.Filters.ActionFilterAttribute.System.Web.Http.Filters.IActionFilter.ExecuteActionFilterAsync(HttpActionContext actionContext, CancellationToken cancellationToken, Func`1 continuation)

any ideas?
this has happened before and i just deleted everything but now.. its abit late to delete all my tree structure.

there is no consistency between document type and then error. its more down to the doc level.

thanks!

umbraco 7.1.8