Cached file credentials lost on xp sp2 laptop (w2k3 DC)

Hi

Last Friday a salesman in our organization who has a laptop and who very rarely connects to the DC (maybe twice a year) received a message he couldn’t log on to his system (he was using cached credentials to login).

I have no idea what might have happened there and since he is not the only person with that setup, is there a known issue and a way to restore his credentials remotely (he’s 7 hours away from our HO) ?

Thanks.