Delete from the page tree fails for one page. When I look in the Console I find the AJAX call to ui/cms/Stores/contentreferences/28?dojo.preventCache=1358239306497 returning a 500 error.

[NullReferenceException: Object reference not set to an instance of an object.]
EPiServer.Cms.Shell.UI.Rest.Models.ContentReferenceModel..ctor(ReferenceInformation reference, IContentLoader contentLoader, IContentVersionRepository contentVersionRepository) +188
EPiServer.Cms.Shell.UI.Rest.ContentReferencesStore.<Get>b__0(ReferenceInformation r) +50
System.Linq.WhereSelectEnumerableIterator`2.MoveNext() +247
System.Collections.Generic.List`1..ctor(IEnumerable`1 collection) +535
System.Linq.Enumerable.ToList(IEnumerable`1 source) +79
Newtonsoft.Json.Serialization.JsonArrayContract.CreateWrapper(Object list) +246
Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty) +441
Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter jsonWriter, Object value) +123
Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter jsonWriter, Object value) +408
System.Web.Mvc.<>c__DisplayClass1a.<InvokeActionResultWithFilters>b__17() +32
System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) +264
System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +853472
EPiServer.Shell.Services.Rest.RestControllerBase.ExecuteCore() +241
System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +334
EPiServer.Shell.Services.Rest.RestHttpHandler.ProcessRequest(HttpContextBase httpContext) +274
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +913
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +165

Ideas?