Outlook VBA doesn't run when machine locked?

I'm using the following code in the ThisOutlookSession object to save file attachments on email messages with a given Subject. It works GREAT if I am working on the machine or have the application minimized. If I get up to walk away, I of course lock my machine. When the machine is locked (Outlook still running in background) and the email comes into my Inbox, the code does not appear to process. Is there way way around this so I don't have to leave my machine unlocked all of the time for it to run?

Thanks
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Private WithEvents objInboxItems As Items

Private Sub Application_Startup()
    Dim objNS As NameSpace
    Set objNS = Application.GetNamespace("MAPI")
    ' instantiate Items collections for folders we want to monitor
    Set objInboxItems = objNS.GetDefaultFolder(olFolderInbox).Items
    Set objNS = Nothing
End Sub

Private Sub Application_Quit()
    ' disassociate global objects declared WithEvents
    Set objInboxItems = Nothing
End Sub

Private Sub objInboxItems_ItemAdd(ByVal Item As Object)
    Dim olItems As Items, _
        olItem As Object, _
        olMailItem As MailItem, _
        olAttachmentItem As Attachment
    Set olItems = objInboxItems.Restrict("[Unread] = True")
    For Each olItem In olItems
        If olItem.Class = olMail Then
            Set olMailItem = olItem
            'Change eeTesting on the next line to the subject you want to key on
            If InStr(1, olMailItem.Subject, "eeTesting", vbTextCompare) > 0 Then
                If olMailItem.Attachments.Count > 0 Then
                    For Each olAttachmentItem In olMailItem.Attachments
                        'Change the path on the next line to the path you want to save your attachments in
                        olAttachmentItem.SaveAsFile "C:\Attachments\" & olAttachmentItem.FileName
                    Next
                End If
            End If
        End If
    Next
End Sub