Hi

I keep getting a null reference error when publishing a page that uses a particular doctype:

[NullReferenceException: Object reference not set to an instance of an object.]
   UmbracoExamine.UmbracoEventManager.content_AfterUpdateDocumentCache(Document sender, DocumentCacheEventArgs e) +27
   umbraco.DocumentCacheEventHandler.Invoke(Document sender, DocumentCacheEventArgs e) +0
   umbraco.content.FireAfterUpdateDocumentCache(Document sender, DocumentCacheEventArgs e) +26
   umbraco.content.UpdateDocumentCache(Document d) +749
   umbraco.content.UpdateDocumentCache(Int32 pageId) +52
   umbraco.library.UpdateDocumentCache(Int32 DocumentId) +106
   umbraco.cms.presentation.editContent.Publish(Object sender, EventArgs e) +383
   System.EventHandler.Invoke(Object sender, EventArgs e) +0
   umbraco.controls.ContentControl.savePublish(Object Sender, ImageClickEventArgs e) +46
   System.Web.UI.WebControls.ImageButton.OnClick(ImageClickEventArgs e) +115
   System.Web.UI.WebControls.ImageButton.RaisePostBackEvent(String eventArgument) +120
   System.Web.UI.WebControls.ImageButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5563

I've seen a topic that has the exact same publishing error http://our.umbraco.org/forum/developers/api-questions/15758-Keep-getting-null-reference-exception-when-publishign-a-node and have tried the suggested fix of renaming any node properties that are conflicting but to no avail.

The particlular doctype I'm using has a property that selects a root media node which is used to list all instances of a custom media type that I have on the site.

I'm wondering if the problem is to do with a conflict between the content node and the media node... could be wrong... worth a shot if anyone has any ideas out there?   help :(