problems with apt-get upgrade

[Richard Swen <rswen@netscape.net>]

I am having problems doing an apt-get upgrade with the following
packages:
  libnspr4 libnss3 mozilla-browser mozilla-psm

each time i try. the following error occurs.

Err http://security.debian.org stable/updates/main mozilla-psm
2:1.7.8-1sarge2
 404 Not Found [IP: 82.94.249.158 80]
Err http://security.debian.org stable/updates/main libnss3 2:1.7.8-1sarge2
 404 Not Found [IP: 82.94.249.158 80]
Err http://security.debian.org stable/updates/main mozilla-browser
2:1.7.8-1sarge2
 404 Not Found [IP: 82.94.249.158 80]

The IP address changes, but the error message remains the same.

Thank you,
Richard Swen