Comment 23 for bug 745304

Eduardo:

Please be aware that pre-released updates have a slight possibility of not working well (that's why they're PRE release, after all).

Your safest bet, if it's not 100% vital for you to have the hibernate functionality right now, is to wait until the 2.6.38-9 kernel makes it into official updates, when that happens, update manager will automatically offer to install it for you. It should only be a few days.

That said, if you want to try your hand at pre-released updates:

1- Go into software center (it has an icon on the Unity panel, on the left side).
2- On the menu, go to Edit -> Software Sources.
3- On the Updates tab, check "Pre-released updates (natty-proposed)".
4- Close the software sources dialog, let software center perform its update process, it will tell you when it's finished.
5- Launch Update Manager.
6- I strongly suggest you uncheck all the updates EXCEPT for the linux-image ones which will install the 2.6.38-9 kernel.
7- Go through the update, restart the system if desired.
8- Once you're up and running with the new kernel, I recommend you disable the pre-released updates by following steps 1-3 and UNchecking natty-proposed. Unless you have a specific reason to want pre-release stuff, it's safer to do it this way.