Ubuntu 10.04 LTS
So awhile back I setup apt to use the linode internal apt cache (http://www.linode.com/wiki/index.php/Internal_Services)
Seeing as incoming bandwidth is no longer counted, not that I used that much, and also the fact that I've been unable to use the internal cache a few times now I decided to remove the /etc/apt/apt.conf.d/01proxy file. Now whenever I attempt to update I'm getting errors.

Err http://us.archive.ubuntu.com lucid-updates/universe Sources
  404  Not Found [IP: 2600:3c03::f03c:91ff:fe93:f238 80]

W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/lucid-updates/main/binary-i386/Packages.gz  404  Not Found [IP: 2600:3c03::f03c:91ff:fe93:f238 80]

2600:3c03::f03c:91ff:fe93:f238 is the local ipv6 address. I can only guess it's still trying to use a proxy without an address so it's using the local IP. I don't have an apt.conf file. I'm at a loss of what to do here, I don't see anything that would tell apt to use a proxy.

This is my apt-config dump

APT "";
APT::Architecture "i386";
APT::Build-Essential "";
APT::Build-Essential:: "build-essential";
APT::Install-Recommends "false";
APT::Install-Suggests "0";
APT::Acquire "";
APT::Acquire::Translation "environment";
APT::NeverAutoRemove "";
APT::NeverAutoRemove:: "^linux-firmware$";
APT::NeverAutoRemove:: "^linux-image.*";
APT::NeverAutoRemove:: "^linux-restricted-modules.*";
APT::NeverAutoRemove:: "^linux-ubuntu-modules-.*";
APT::Never-MarkAuto-Sections "";
APT::Never-MarkAuto-Sections:: "metapackages";
APT::Never-MarkAuto-Sections:: "restricted/metapackages";
APT::Never-MarkAuto-Sections:: "universe/metapackages";
APT::Never-MarkAuto-Sections:: "multiverse/metapackages";
APT::Never-MarkAuto-Sections:: "oldlibs";
APT::Never-MarkAuto-Sections:: "restricted/oldlibs";
APT::Never-MarkAuto-Sections:: "universe/oldlibs";
APT::Never-MarkAuto-Sections:: "multiverse/oldlibs";
Dir "/";
Dir::State "var/lib/apt/";
Dir::State::lists "lists/";
Dir::State::cdroms "cdroms.list";
Dir::State::mirrors "mirrors/";
Dir::State::userstatus "status.user";
Dir::State::status "/var/lib/dpkg/status";
Dir::Cache "var/cache/apt/";
Dir::Cache::archives "archives/";
Dir::Cache::srcpkgcache "srcpkgcache.bin";
Dir::Cache::pkgcache "pkgcache.bin";
Dir::Etc "etc/apt/";
Dir::Etc::sourcelist "sources.list";
Dir::Etc::sourceparts "sources.list.d";
Dir::Etc::vendorlist "vendors.list";
Dir::Etc::vendorparts "vendors.list.d";
Dir::Etc::main "apt.conf";
Dir::Etc::netrc "auth.conf";
Dir::Etc::parts "apt.conf.d";
Dir::Etc::preferences "preferences";
Dir::Etc::preferencesparts "preferences.d";
Dir::Bin "";
Dir::Bin::methods "/usr/lib/apt/methods";
Dir::Bin::dpkg "/usr/bin/dpkg";
Dir::Media "";
Dir::Media::MountPath "/media/apt";
Dir::Log "var/log/apt";
Dir::Log::Terminal "term.log";
Dir::Log::History "history.log";
aptitude "";
aptitude::Keep-Unused-Pattern "^linux-image.*$ | ^linux-restricted-modules.*$ | ^linux-ubuntu-modules.*$";
aptitude::Get-Root-Command "sudo:/usr/bin/sudo";
DPkg "";
DPkg::Pre-Install-Pkgs "";
DPkg::Pre-Install-Pkgs:: "/usr/sbin/dpkg-preconfigure --apt || true";

Weird thing to add here. Changing my sources.list to use ftp instead of http has worked around the issue. Not sure why http doesn't work still.
I don't see anything in the enviroment variables that would use a proxy, and I can use lynx to connect to security.ubuntu.com normally.