OMA and error 1503 at random   

hi there
i am running Windows 2003 Std edition with Exchange 2003 Std.
OMA was working fine for ages and then suddenly stopped.  When I
restart the IIS services it all works normally again for a while and
then stops.  When I look in the event log i get error 1503 with the
following details

An unknown error occurred while processing the current request:
Message: Object reference not set to an instance of an object.
Source: System
Stack trace:
   at System.Net.OSSOCK.recv(IntPtr socketHandle, IntPtr pinnedBuffer,
Int32 len, SocketFlags socketFlags)
   at System.Net.Sockets.Socket.Receive(Byte[] buffer, Int32 offset,
Int32 size, SocketFlags socketFlags)
   at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32
offset, Int32 size)

Message: Unable to read data from the transport connection.
Source: System
Stack trace:
   at System.Net.ConnectStream.BeginRead(Byte[] buffer, Int32 offset,
Int32 size, AsyncCallback callback, Object state)
   at System.Net.ConnectStream.Read(Byte[] buffer, Int32 offset, Int32
size)
   at System.Xml.XmlStreamReader.Read(Byte[] data, Int32 offset, Int32
length)
   at System.Xml.XmlScanner.Read()
   at System.Xml.XmlScanner.ScanContent()
   at System.Xml.XmlTextReader.ParseRoot()
   at System.Xml.XmlTextReader.Read()
   at
Microsoft.Exchange.OMA.ExchangeDataProvider.StaticStuff.ParseDavResponse(Stream
response, NewItemDelegate newItem, AddItemDelegate addItem,
StatusDelegate handleStatus)
   at
Microsoft.Exchange.OMA.ExchangeDataProvider.ExchangeItem.PopulateProperties(IList
RequestedProperties, Boolean NoPreferences)
   at
Microsoft.Exchange.OMA.ExchangeDataProvider.ExchangeItem.PopulateProperties(IList
RequestedProperties)
   at Microsoft.Exchange.OMA.UserInterface.MainMenu.OnInit(EventArgs
e)
   at System.Web.UI.Control.InitRecursive(Control namingContainer)
   at System.Web.UI.Control.AddedControl(Control control, Int32 index)
   at System.Web.UI.MobileControls.MobilePage.AddedControl(Control
control, Int32 index)
   at System.Web.UI.ControlCollection.Add(Control child)
   at Microsoft.Exchange.OMA.UserInterface.Form.SwitchForms(Form form)
   at
Microsoft.Exchange.OMA.UserInterface.UnsupportedDevice.OkClick(Object
sender, EventArgs e)
   at System.Web.UI.MobileControls.Command.OnClick(EventArgs e)
   at
System.Web.UI.MobileControls.Command.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String
argument)
   at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler
sourceControl, String eventArgument)
   at
System.Web.UI.MobileControls.MobilePage.RaisePostBackEvent(IPostBackEventHandler
sourceControl, String eventArgument)
   at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection
postData)
   at System.Web.UI.Page.ProcessRequestMain()

Message: Exception of type System.Web.HttpUnhandledException was
thrown.
Source: System.Web
Stack trace:
   at System.Web.UI.Page.HandleError(Exception e)
   at System.Web.UI.Page.ProcessRequestMain()
   at System.Web.UI.Page.ProcessRequest()
   at System.Web.UI.Page.ProcessRequest(HttpContext context)
   at System.Web.CallHandlerExecutionStep.System.Web.HttpApplication
+IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step,
Boolean& completedSynchronously)


Can anybody advise?
thanks

date: Sun, 16 Mar 2008 12:02:03 -0700 (PDT)   author:   shnax