I couldn't switch to 2.6.28-13-generic Kernel on jaunty because the nvidia graphics driver kernel modules couldn't be compiled by dkms:
Examining /etc/kernel/postinst.d. run-parts: executing /etc/kernel/postinst.d/dkms * Running DKMS auto installation service for kernel 2.6.28-13-generic * nvidia (180.44)...nvidia (180.44): Installing module. .....(bad exit status: 6) Build failed. Installation skipped.
Today I finally had time to inspect the problem, and found out the reason, and a very simple fix as well. This happened because "patch" wasn't installed.
So, typing those two commands fixed all problems:
sudo apt-get install patch sudo dpkg-reconfigure linux-image-2.6.28-13-generic
In case anyone is stuck in the same place, try it out and let me know if it worked ...