Trapping Process starts using WMI

[Guest]

I've a requirement to monitor when certain applications are started. I'm
using WMI called from VS Stusio 2005 in VB to trap Excel and Word starting.
I've written the following console application which wires up 4 events to
trap Excel/Word Start/Stop events. The application works fine for Excel but
Word behaves strangely. When I start an instance of Word I get the correct
message displayed in the console. When I start a second instance of Word I
get the Stop event fired (rather then the Start) - the console looks like
this
after the second instance is started - ie an immediate stop event and stop
message.

press <enter> to stop...
Application=Word, Start, Parent Process Id=324, Process Id=4776
Application=Word, Start, Parent Process Id=324, Process Id=5236
Application=Word, Stop, Parent Process Id=324, Process Id=5236

any help appreciated. The code is attached.
thanks

Imports System
Imports System.Management

Module TaskMonitor

Dim Applications As New ApplicationCollection

Dim WordStartWatcher As ManagementEventWatcher
Dim WordStopWatcher As ManagementEventWatcher
Dim ExcelStartWatcher As ManagementEventWatcher
Dim ExcelStopWatcher As ManagementEventWatcher

Sub Main()

StartWatching()

Console.WriteLine("press <enter> to stop...")
Console.ReadLine()

StopWatching()

End Sub

Private Sub StartWatching()

WordStartWatcher = New
ManagementEventWatcher(GenerateStartQuery("WINWORD.EXE"))
AddHandler WordStartWatcher.EventArrived, AddressOf WordStarted
WordStartWatcher.Start()

WordStopWatcher = New
ManagementEventWatcher(GenerateStopQuery("WINWORD.EXE"))
AddHandler WordStopWatcher.EventArrived, AddressOf WordStopped
WordStopWatcher.Start()

ExcelStartWatcher = New
ManagementEventWatcher(GenerateStartQuery("EXCEL.EXE"))
AddHandler ExcelStartWatcher.EventArrived, AddressOf ExcelStarted
ExcelStartWatcher.Start()

ExcelStopWatcher = New
ManagementEventWatcher(GenerateStopQuery("EXCEL.EXE"))
AddHandler ExcelStopWatcher.EventArrived, AddressOf ExcelStopped
ExcelStopWatcher.Start()

End Sub

Private Sub StopWatching()

WordStartWatcher.Stop()
RemoveHandler WordStartWatcher.EventArrived, AddressOf WordStarted
WordStartWatcher = Nothing

WordStopWatcher.Stop()
RemoveHandler WordStopWatcher.EventArrived, AddressOf WordStopped
WordStopWatcher = Nothing

ExcelStartWatcher.Stop()
RemoveHandler ExcelStartWatcher.EventArrived, AddressOf ExcelStarted
ExcelStartWatcher = Nothing

ExcelStopWatcher.Stop()
RemoveHandler ExcelStopWatcher.EventArrived, AddressOf ExcelStopped
ExcelStopWatcher = Nothing

End Sub

Public Sub WordStarted(ByVal sender As Object, ByVal e As
EventArrivedEventArgs)

Applications.Add(e.NewEvent.Properties("ProcessID").Value, New
Word(e.NewEvent.Properties("ParentProcessID").Value,
e.NewEvent.Properties("ProcessID").Value))
Console.WriteLine(String.Concat("Application=Word, Start, Parent
Process Id=", e.NewEvent.Properties("ParentProcessID").Value.ToString, ",
Process Id=", e.NewEvent.Properties("ProcessID").Value.ToString))

End Sub

Public Sub WordStopped(ByVal sender As Object, ByVal e As
EventArrivedEventArgs)

If
Applications.ContainsKey(e.NewEvent.Properties("ProcessID").Value) Then
Applications.Remove(e.NewEvent.Properties("ProcessID").Value)
End If

Console.WriteLine(String.Concat("Application=Word, Stop, Parent
Process Id=", e.NewEvent.Properties("ParentProcessID").Value.ToString, ",
Process Id=", e.NewEvent.Properties("ProcessID").Value.ToString))

End Sub

Public Sub ExcelStarted(ByVal sender As Object, ByVal e As
EventArrivedEventArgs)

Applications.Add(e.NewEvent.Properties("ProcessID").Value, New
Word(e.NewEvent.Properties("ParentProcessID").Value,
e.NewEvent.Properties("ProcessID").Value))
Console.WriteLine(String.Concat("Application=Excel, Start, Parent
Process Id=", e.NewEvent.Properties("ParentProcessID").Value.ToString, ",
Process Id=", e.NewEvent.Properties("ProcessID").Value.ToString))

End Sub

Public Sub ExcelStopped(ByVal sender As Object, ByVal e As
EventArrivedEventArgs)

If
Applications.ContainsKey(e.NewEvent.Properties("ProcessID").Value) Then
Applications.Remove(e.NewEvent.Properties("ProcessID").Value)
End If

Console.WriteLine(String.Concat("Application=Excel, Stop, Parent
Process Id=", e.NewEvent.Properties("ParentProcessID").Value.ToString, ",
Process Id=", e.NewEvent.Properties("ProcessID").Value.ToString))

End Sub

Private Function GenerateStartQuery(ByVal ProcessName As String) As
WqlEventQuery
Dim ApplicationStartQuery As New WqlEventQuery
ApplicationStartQuery.EventClassName = "Win32_ProcessStartTrace"
ApplicationStartQuery.QueryString = String.Concat("SELECT * FROM
Win32_ProcessStartTrace where ProcessName = ", """", ProcessName, """")
Return ApplicationStartQuery
End Function

Private Function GenerateStopQuery(ByVal ProcessName As String) As
WqlEventQuery
Dim ApplicationStopQuery As New WqlEventQuery
ApplicationStopQuery.EventClassName = "Win32_ProcessStopTrace"
ApplicationStopQuery.QueryString = String.Concat("SELECT * FROM
Win32_ProcessStopTrace where ProcessName = ", """", ProcessName, """")
Return ApplicationStopQuery
End Function

End Module