It looks to me like the index files get corrupted during download. Can you try a different provider, or a 3G connection, to ensure it's not the ISP mangling the files?
** Changed in: apt (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/919204 Title: Problems with the update manager/apt-get/synaptic in Ubuntu 11.10 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/apt/+bug/919204/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs