Comment 21 for bug 855171

Yes, the update caused some mighty weird behaviour, including making network-manager disappear. Synaptic said that libnss3 was installed, even though libnss3's properties told me it couldn't tell me the list of installed files because the package wasn't installed. So reinstalling it from Synaptic made no difference.

In the end I was able to reinstall it using dpkg -i on the cached deb file in /var/cache/apt/archives.