[rhn-users] Up2date fails with "Forbidden"

[Ziriax John M Civ NHRC/DET <John Ziriax brooks af mil>]

up2date was working on this machine, but not for some reason it fails with
the following message:

Error communicating with server. The message was:
Forbidden


It is a RH 9 system with the firewall turned off that is working through an
HTTP proxy. A second computer works fine.

I need a hint as to how to start analyzing this problem.

Thanks

John