Im on ubuntu 10.04. with kernel version 2.6.32-34. I need to downgrade the kernel version to 18.104.22.168. How do I do this?
Linux supermace 2.6.32-34-generic-pae #77-Ubuntu SMP Tue Sep 13 21:16:18 UTC 2011 i686 GNU/Linux
Open Package Manager (Synaptic) and see if that kernel is still present in repository:
If exists you can install it, along with newest kernel, and at boot time you can select "Previous Linux versions", then the 2.6.32-25 version. You could also completely delete the 2.6.32-34, however it's not a good idea as it's supposed to be better than old.
If the kernel is not in repository, the installation procedure is more difficult, and I would not go that way.