Debian 5.0 (lenny) apt sources fail?

For the past few days, I couldn't update our apt-sources on Debian 5.0 (lenny). I get the following errors.

W: Failed to fetch http://ftp.debian.org/debian/dists/lenny/main/binary-amd64/Packages  404 Not Found [IP: 130.89.148.12 80]

W: Failed to fetch http://ftp.debian.org/debian/dists/lenny/contrib/binary-amd64/Packages  404 Not Found [IP: 130.89.148.12 80]

W: Failed to fetch http://ftp.debian.org/debian/dists/lenny/non-free/binary-amd64/Packages  404 Not Found [IP: 130.89.148.12 80]

W: Failed to fetch http://ftp.debian.org/debian/dists/lenny/main/source/Sources  404 Not Found [IP: 130.89.148.12 80]

W: Failed to fetch http://ftp.debian.org/debian/dists/lenny/contrib/source/Sources  404 Not Found [IP: 130.89.148.12 80]

W: Failed to fetch http://ftp.debian.org/debian/dists/lenny/non-free/source/Sources  404 Not Found [IP: 130.89.148.12 80]

How do I fix this problem?

Edit:

My current sources are:

# Debian Lenny
deb http://ftp.de.debian.org/debian/ lenny main non-free contrib  
deb-src http://ftp.de.debian.org/debian/ lenny main non-free contrib  

# Debian Lenny Non-US
deb http://non-us.debian.org/debian-non-US lenny/non-US main contrib non-free  
deb-src http://non-us.debian.org/debian-non-US lenny/non-US main contrib non-free

# Debian Lenny Security
deb http://security.debian.org/ lenny/updates main contrib non-free

Solution 1:

lenny is superseded by squeeze, and its lifecycle ended on Feb. 6th this year. You'll get no updates from the core Debian community for lenny.

Options:

1. Upgrade to squeeze.
2. Stay with lenny, remove the Debian FTP servers from sources.list and keep the packages as they are. There will be no security updates.
3. Pin (man apt_preferences) necessary packages down to lenny and perform a partial upgrade, or pin all packages down to lenny and perform upgrades as needed. Leaves you with a partial system, and you are likely to get all kinds of errors, but might be necessary if neither upgrade nor keep-as-is are options.

Solution 2:

You can use the following sources until you upgrade your system:

deb http://archive.debian.org/debian/ lenny contrib main non-free

Solution 3:

archive.debian.org has the package repositories of all EOLd debian releases