ok I have more information for support to help me troubleshoot.
so far we have worked out that;
1. The issue has nothing to do with the UNC as I have received the same error on local disk as well as UNC
2. The issue has nothing to do with the 3889AC4AF542BAC3C62ABB154E78FEA8.dll inside either BIN or SiteFinity/ServiceAssemblies as I totally removed both and eventually got the same error.
I then added some logging script to the Application_Error event in Global.asax and waited for it to happen again...which it has and I have the following error information below.
Note: Pingdom checks the site /Home.aspx url every 5 minutes and sends me an error alert if down (which has been once a day since the upgrade). It does not access /sitefinity/cmsentrypoint.aspx as the error below suggests..all I can think of here is that Home.aspx calls /sitefinity/cmsentrypoint.aspx within the page?
To temporary resolve the issue all I do is rename one of the dlls, then rename it back. It then recompiles and sorts itself out. Seems as any change to the BIN directory will temporary resolve the issue
DateTime: Thursday, 16 July 2009 4:43:21 PM
Offending URL: /sitefinity/cmsentrypoint.aspx
Machine Name: GANYMEDE
User Agent: Pingdom.com_bot_version_1.4_(http://www.pingdom.com/)
Message: Exception of type 'System.Web.HttpUnhandledException' was thrown.
Stack trace: at System.Web.UI.Page.HandleError(Exception e) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) at System.Web.UI.Page.ProcessRequest() at System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context) at System.Web.UI.Page.ProcessRequest(HttpContext context) at ASP.sitefinity_cmsentrypoint_aspx.ProcessRequest(HttpContext context) at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
Inner Exception: System.NullReferenceException: Object reference not set to an instance of an object. at Nolics.ORMapper.DataProviders.SQLDataProvider.ParseResult(Int32 fromRow, Int32 maxRows, DataSet dsResult, IDataReader rd) at Nolics.ORMapper.DataProviders.SQLDataProvider.ExecuteKeyQuery(DataSet queries, Boolean fPrimaryKey) at Nolics.ORMapper.DataProviders.SQLDataProvider.QueryByPrimaryKey(DataSet keys) at Nolics.ORMapper.Base.PrimeryKeyQuery.LoadPKQuery() at Nolics.ORMapper.Base.LinkToValue`1.Resolve(ObKey key, IOdbView fromClass) at Telerik.Cms.Data.PageContentBase.get_Page() at Telerik.Cms.Data.CmsPageContent.get_CmsPage() at Telerik.Cms.Data.CmsPageContent.get_DisableViewState() at Telerik.Cms.Web.InternalPage.SetPageSettings(ICmsPage cmsPage) at Telerik.Cms.Web.InternalPage.OnPreInit(EventArgs e) at System.Web.UI.Page.PerformPreInit() at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)