How do you set the root in 1.5? I notice there's no setting for it in the forum settings section - but the instruction video shows there is.

My structure is:

Home

-- Simple Website

--- Page 1
--- Page 2

-- Forum

I'm getting a

Object reference not set to an instance of an object error

[NullReferenceException: Object reference not set to an instance of an object.]
   nForum.BusinessLogic.Models.NodeMapper.MapForumCategory(INode nodetomap) +137
   nForum.usercontrols.nForum.ForumListPostsInTopic.GetTopicPosts() +174
   nForum.usercontrols.nForum.ForumListPostsInTopic.Page_Load(Object sender, EventArgs e) +52
   System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35
   System.Web.UI.Control.OnLoad(EventArgs e) +91
   System.Web.UI.Control.LoadRecursive() +74
   System.Web.UI.Control.LoadRecursive() +146
   System.Web.UI.Control.LoadRecursive() +146
   System.Web.UI.Control.LoadRecursive() +146
   System.Web.UI.Control.LoadRecursive() +146
   System.Web.UI.Control.LoadRecursive() +146
   System.Web.UI.Control.LoadRecursive() +146
   System.Web.UI.Control.LoadRecursive() +146
   System.Web.UI.Control.LoadRecursive() +146
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2207

When you click on a topic title I get the above error. This was from fresh install.