>>Where does lFirstHit get set to False ?
>
>In EndRequest(), which is executed at the end:
>
>

>        ' Execute at the end of each hit
>        Public Function EndRequest() As Boolean
>
>            ' If this is the first hit
>            If lFirstHit Then
>                lFirstHit = False
>            End If
>

Can't pin it down but that feels a bit risky in that lFirstHit itself is not thread safe. And I'm also not sure whether taking a lock on a property of oApp itself is good. Best practice might be something like this:

If Not oApp.lInitialize Then
        SyncLock locker
            'Check again inside safe section
            If Not oApp.lInitialize Then
                'Do stuff
                oApp.lInitialize = True
            End If
        End SyncLock
  End If
'Where locker is:
Private Shared locker As New [Object]()

No guarantees :-}

UPDATE: I mocked this and don't think the use of the oApp property as the monitor would be a problem. But what is critical is the need to *recheck* the conditional value (in this case oApp.lInitialize) once the lock is obtained.