Hi.

This is for a site that has been running uneventfully for a while. Today when I try to access it I get Object reference not set errors on every page (apart from on a .net diagnostic page in a folder umbraco doesn't run).

The only page I can see is the login, which has lost all of its css.

When I try to login the page refreshes, giving no error messages of any kind, and failing to log me in.

I have changed the connectionstring and when I do so I get "network service" error messages, so I think the connectionstring is correct.

here's my error.

[NullReferenceException: Object reference not set to an instance of an object.]
   umbraco.requestHandler..ctor(XmlDocument umbracoContent, String url) +1175
   umbraco.UmbracoDefault.Page_PreInit(Object sender, EventArgs e) +1062
   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.EventHandler.Invoke(Object sender, EventArgs e) +0
   System.Web.UI.Page.OnPreInit(EventArgs e) +9010534
   System.Web.UI.Page.PerformPreInit() +31
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +328

Where should I look first?