I am getting the following error when republishing any branch of my content tree. This whole issue came about when I noticed that a macro that renders nodes that I've removed still including them and thus should no longer be included. The good news is that there's no evidence of this error on the web site side, except for presence of the nodes I wish to unpublish.

Where do I start to fix this?

[quote]Server Error in '/' Application.
Object reference not set to an instance of an object.
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.NullReferenceException: Object reference not set to an instance of an object.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[NullReferenceException: Object reference not set to an instance of an object.]
umbraco.cms.businesslogic.Content.createNewVersion() +68
umbraco.cms.businesslogic.web.Document.PublishWithResult(User u) +114
umbraco.dialogs.publish.doPublishSubs(Document d) +60
umbraco.dialogs.publish.doPublishSubs(Document d) +267
umbraco.dialogs.publish.doPublishSubs(Document d) +267
umbraco.dialogs.publish.Page_Load(Object sender, EventArgs e) +1058
System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +15
System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +33
System.Web.UI.Control.OnLoad(EventArgs e) +99
umbraco.BasePages.BasePage.OnLoad(EventArgs e) +12
System.Web.UI.Control.LoadRecursive() +47
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1436


Version Information: Microsoft .NET Framework Version:2.0.50727.1433; ASP.NET Version:2.0.50727.1433 [/quote]