> I've seen this too and it seems that it is happening when they logoff. I
> get my own username in there and I know that I am not making a mistake on
> the username and password because it has not changed.
And I bet you are using Win95? I have seen this one as well with
Microsoft PPP clients. When you manually terminate the session from
the Client side, the client will send a PAP request (don't ask me how)
with a blank password. Its one of those really bizzare things!