I installed a pae kernel on my Ubuntu 12.04 32-bit box in order to try it (I thought I would add RAM to my computer which I finaly didn't).
It automatically added an entry to grub's boot menu with the pae kernel, which is now the default one.
Now I don't use it any more (just gave it a try). Now every time I boot, I select "previous linux versions" in the boot menu, and then in the submenu I choose the first entry, which used to be the default one prior to installing the PAE kernel.
Now if I uninstall the kernel with apt-get remove (as I installed it with apt-get install), I obviously expect it to leave everything the way it was before: i.e., remove the corresponding item in the boot menu and restore the old one as the default.
The question is: will it do that? I want to be sure that I won't end up with an unbootable machine with an entry in the boot menu for a kernel that is uninstalled, causing grup to freak out or something, or (less disastrous but still annoying) with a useless entry in the boot menu obliging me to choose the right option every time forever as I do now (or to manually reconfigure grup).