What do these command do?
sudo apt-get install linux-image-generic-lts-backport-natty \
linux-headers-generic-lts-backport-natty
Does it install just a new Linux version or something more?
And what about:
sudo apt-get purge linux-image-generic-lts-backport-natty \
linux-headers-generic-lts-backport-natty
Does it just remove the packages installed by the previous command? (or does it more?)
If I am correct in all cases why it doesn't work? I get an error, so it means it's not true and something else had happened?
Edit:
as it was said that second command doesn't remove it, then would this command remove it? aptitude autoremove

installcommand installed the meta package as well as the kernel as it always depends on the kernel but yourpurgecommand only removed the meta package but not the kernel itself AFAIK. – sagarchalise Dec 22 '11 at 17:37autoremovewould remove the unnecessary packages but Since I don't know what you are trying to achieve. I recommend you to boot from an older kernel if you have one or force downgrade your kernel. Could you paste the output ofuname -a– sagarchalise Dec 22 '11 at 18:12