unhandled nullexception

[ak...@nreca.org]

I have a service that has a thread that uses msmq. Service starts and
works fine but if I leave it run overnight it fails during the night.
This thread uses a system.timers.timer which expires every 60
seconds. When it fails it write the following to the eventlog:

Application: WindowsService1.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.NullReferenceException
Stack:
at System.Messaging.Cursor.Finalize()

Can't figure out where this is coming from. Here is the main part of
my code:

Public Sub Starter()
WriteToEventLog("PendedEvent thread is starting....",
LogSource, EventLogEntryType.Information)

MailHelper = New EmailHelper

' Use the same Quiet Start and End times retrieved by the
main thread
MailHelper.QuietStart = QuietStart
MailHelper.QuietEnd = QuietEnd

' Process then sleep
If Not MQin.Equals(Nothing) Then
PendedTimer = New Timers.Timer
AddHandler PendedTimer.Elapsed, New
ElapsedEventHandler(AddressOf PendedTimerHandler)
CalcInterval(TimeIncrement)
PendedTimer.Start()
End If

End Sub

Protected Sub PendedTimerHandler(ByVal sender As Object, ByVal e
As ElapsedEventArgs)
' Handles the event when the timer expires

Dim Time_Span As TimeSpan = New TimeSpan(10000)
Dim ArriveTime As DateTime = Now
Dim SomethingInQue As Boolean = True
Dim M As Message = Nothing
Dim FirstLoop As Boolean = True
Dim Qcursor As Cursor = Nothing

AddMessage(ErrorMessage, "PendedHandler starting")
WriteToEventLog(ErrorMessage, LogSource,
EventLogEntryType.Information)
ErrorMessage = ""

Try
PendedTimer.Stop()
Qcursor = MQin.CreateCursor

' Tell the object we want the 'ArrivedTime' property when
we peek
MQin.MessageReadPropertyFilter.ArrivedTime = True

AddMessage(ErrorMessage, "Starting queue peek")
WriteToEventLog(ErrorMessage, LogSource,
EventLogEntryType.Information)
ErrorMessage = ""

' First, check the queue
Do While SomethingInQue
Try
If FirstLoop Then
MQin.Peek(Time_Span, Qcursor,
PeekAction.Current) ' This will fall to "catch" if nothing
in the queue
FirstLoop = False
Else
MQin.Peek(Time_Span, Qcursor, PeekAction.Next)
End If

' Check to see when it arrived in the queue
ArriveTime = MQin.Peek.ArrivedTime

Catch mqe As MessageQueueException
If mqe.MessageQueueErrorCode =
MessageQueueErrorCode.IOTimeout Then
' Tomeout occured so there are no messages to
process
SomethingInQue = False

AddMessage(ErrorMessage, "Nothing in queue")
WriteToEventLog(ErrorMessage, LogSource,
EventLogEntryType.Information)
ErrorMessage = ""

Exit Do
End If
Catch ex As Exception
SomethingInQue = False
AddMessage(ErrorMessage, "Error processing MSMQ
'peek'" & vbCrLf & vbCrLf & ex.Message)
Exit Do
End Try

Process_Pended_Event(MQin.Peek.Body.ToString)

' If it's more than two days old report it stagnate
If Not PreviousMessageRemoved Then
If ArriveTime.AddDays(2) < Today Then
' Let someone know we have a transaction that
is stuck because of no company
' But first find out if we've alrady sent a
message today
If CheckSent() Then
If Not AlreadySentToday Then
AddMessage(ErrorMessage, "NewHire: a
subgroup has not been found in the Xref table for more than two days")
UpdateEmailLastSent()
End If
End If
End If
End If
Loop

If ErrorMessage.Length <> 0 Then
MailHelper.SendSupportEmail(SQLcmd, ErrorMessage,
IsProd)
RecordEmail(MQin.Peek.Body.ToString)
End If

RestartTimer()

Catch ex As Exception
AddMessage(ErrorMessage, "PendedTimerHandler: Outer trap "
& vbCrLf & ex.Message)
End Try

End Sub

Anyone have any ideas?