doing a refresh on the commandline works fine:
$ sudo aptitude update
[sudo] password for lothar:
Hit http://security.ubuntu.com lucid-security Release.gpg
Ign http://security.ubuntu.com/ubuntu/ lucid-security/main Translation-en_US
Hit http://archive.canonical.com lucid Release.gpg
Ign http://archive.canonical.com/ubuntu/ lucid/partner Translation-en_US
Get:1 http://us.archive.ubuntu.com lucid Release.gpg [189B]
Ign http://us.archive.ubuntu.com/ubuntu/ lucid/main Translation-en_US
Ign http://security.ubuntu.com/ubuntu/ lucid-security/restricted
Translation-en_US
Ign http://security.ubuntu.com/ubuntu/ lucid-security/universe
Translation-en_US
Ign http://security.ubuntu.com/ubuntu/ lucid-security/multiverse
Translation-en_US
Hit http://security.ubuntu.com lucid-security Release
Hit http://archive.canonical.com lucid Release
Ign http://us.archive.ubuntu.com/ubuntu/ lucid/restricted Translation-en_US
Ign http://us.archive.ubuntu.com/ubuntu/ lucid/universe Translation-en_US
Ign http://us.archive.ubuntu.com/ubuntu/ lucid/multiverse Translation-en_US
Hit http://us.archive.ubuntu.com lucid-updates Release.gpg
Ign http://us.archive.ubuntu.com/ubuntu/ lucid-updates/main Translation-en_US
Ign http://us.archive.ubuntu.com/ubuntu/ lucid-updates/restricted
Translation-en_US
Ign http://us.archive.ubuntu.com/ubuntu/ lucid-updates/universe
Translation-en_US
Ign http://us.archive.ubuntu.com/ubuntu/ lucid-updates/multiverse
Translation-en_US
Hit http://security.ubuntu.com lucid-security/main Packages
Hit http://archive.canonical.com lucid/partner Packages
Hit http://us.archive.ubuntu.com lucid-proposed Release.gpg
Ign http://us.archive.ubuntu.com/ubuntu/ lucid-proposed/restricted
Translation-en_US
Ign http://us.archive.ubuntu.com/ubuntu/ lucid-proposed/main Translation-en_US
Ign http://us.archive.ubuntu.com/ubuntu/ lucid-proposed/multiverse
Translation-en_US
Ign http://us.archive.ubuntu.com/ubuntu/ lucid-proposed/universe
Translation-en_US
Hit http://security.ubuntu.com lucid-security/restricted Packages
Hit http://security.ubuntu.com lucid-security/main Sources
Hit http://security.ubuntu.com lucid-security/restricted Sources
Hit http://security.ubuntu.com lucid-security/universe Packages
Get:2 http://us.archive.ubuntu.com lucid Release [57.2kB]
Hit http://security.ubuntu.com lucid-security/universe Sources
Hit http://security.ubuntu.com lucid-security/multiverse Packages
Hit http://security.ubuntu.com lucid-security/multiverse Sources
Hit http://us.archive.ubuntu.com lucid-updates Release
Hit http://us.archive.ubuntu.com lucid-proposed Release
Get:3 http://us.archive.ubuntu.com lucid/main Packages [1,387kB]
Get:4 http://us.archive.ubuntu.com lucid/restricted Packages [6,189B]
Get:5 http://us.archive.ubuntu.com lucid/main Sources [659kB]
Get:6 http://us.archive.ubuntu.com lucid/restricted Sources [3,761B]
Get:7 http://us.archive.ubuntu.com lucid/universe Packages [5,451kB]
Err http://packages.medibuntu.org lucid Release.gpg
Could not connect to packages.medibuntu.org:80 (88.191.82.11). - connect
(110: Connection timed out)
Err http://packages.medibuntu.org/ lucid/free Translation-en_US