@Duke5A - That's a good alternative fix there. It would also make sense as the problem only happens on wireless and not wired workstations, all from the same image (in my case).
@Little-Miss - Is the problem resolved? Hopefully most of your netbooks have 'checked in' to receive the updated policy settings.
To be honest, it hadn't when i tried. Like @Duke5A said, its completely random. It may well have worked now...the proof will be when one ends up on my desk again :). But will keep the other option in mind too.