I get the following error when doing a 'aptitude update' on a Debian 
Etch box.  Before I email ftp-master@??? with the problem am I 
doing something stupid?  I have repeatedly run aptitude update and the 
error persists...
Simon C.
my-host:~# aptitude update
Get:1 
http://ftp.uk.debian.org etch Release.gpg [378B]
Hit 
http://ftp.uk.debian.org etch Release
Get:2 
http://www.backports.org etch-backports Release.gpg [189B]
Ign 
http://ftp.uk.debian.org etch/main Packages/DiffIndex
Get:3 
http://www.backports.org etch-backports Release
Ign 
http://ftp.uk.debian.org etch/main Sources/DiffIndex
Ign 
http://www.backports.org etch-backports Release
Hit 
http://ftp.uk.debian.org etch/main Packages
Get:4 
http://www.backports.org etch-backports/main Packages [450kB]
Hit 
http://ftp.uk.debian.org etch/main Sources
Get:5 
http://security.debian.org etch/updates Release.gpg [189B]
Hit 
ftp://mirror.ox.ac.uk etch Release.gpg
Get:6 
ftp://mirror.ox.ac.uk etch Release [58.2kB]
Hit 
http://security.debian.org etch/updates Release
Ign 
http://security.debian.org etch/updates/main Packages/DiffIndex
Hit 
http://security.debian.org etch/updates/main Packages
Get:7 
ftp://mirror.ox.ac.uk etch/main Packages/DiffIndex
Ign 
ftp://mirror.ox.ac.uk etch/main Packages/DiffIndex
Get:8 
ftp://mirror.ox.ac.uk etch/main Sources/DiffIndex
Ign 
ftp://mirror.ox.ac.uk etch/main Sources/DiffIndex
Hit 
ftp://mirror.ox.ac.uk etch/main Packages
Hit 
ftp://mirror.ox.ac.uk etch/main Sources
Fetched 508kB in 2s (179kB/s)
Reading package lists... Done
W: GPG error: 
http://www.backports.org etch-backports Release: The 
following signatures were invalid: BADSIG EA8E8B2116BA136C Backports.org 
Archive Key <ftp-master@???>
W: You may want to run apt-get update to correct these problems