Comment 45 for bug 155393

My experience was definitely a different bug than this one (since it went away by disabling ipv6), and was fixed by issue 156720. https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/156720/ Sorry for adding to the confusion.

At this point the easiest way to distinguish between that bug (156720) and other problems is to upgrade to libc6 2.6.1-1ubuntu10 from gutsy-updates for your platform. If update manager / synaptic, etc can't download these files, the ones you need for a default i686 installation are:
http://archive.ubuntu.com/ubuntu/pool/main/g/glibc/libc6_2.6.1-1ubuntu10_i386.deb
http://archive.ubuntu.com/ubuntu/pool/main/g/glibc/libc6-i686_2.6.1-1ubuntu10_i386.deb