Can i upgrade my linux Kernel 2.6.38 to the new one 18.104.22.168? Is it safe and stable to upgrade it in my Ubuntu Natty?
The Ubuntu Kernel team have a PPA which they maintain with the latest version of the kernel for Natty - having just checked, the current version in the repo is 2.6.39-0.5
If you want to test more vanilla Kernel Builds then the kernel team also do nightly builds as well as builds for each release candidate.
For example - the new v3 kernel builds are available - these are tagged as -oneric. Obviously these builds are specifically been built for the next version of ubuntu in mind. Also, if you install them, you'll need to keep up-to-date yourself.
Change info for Kernel 2.6.39
However - there is little point in upgrading a kernel unless you are having serious issues with you current official Natty kernel. What do you expect to gain?
Is it "safe and stable" - arguable terms. Linus T calls it stable. There are many thousands of users using 2.6.38 in Natty and many of the latest distros.
i advise to get it one step forward and install kernel 3.0.0 (also known as 2.6.40 but officially it's 3.0) It's release candidate and so far working perfectly for me (fixing described above bug with radeon)
I installed it.
NOT stable, had serious issues with my ATI card, ran occasionally with Unity but usually just failed to load the GUI, ran OK in Failsafe mode - but what fun is that?
I'm anything but an expert but I had a lot of difficulty getting back to the previous kernel.
Obviosly works for some, but unless you are prepared for fun and games ....