You might need to reinstall the boot loader to the master boot record (MBR) if it becomes corrupted or erased. This can occur for example if Windows is installed on another partition which overwrites the MBR. There are two ways to reinstall grub, automatically using grub-install, and manually through grub itself. grub-install is a script [...]

Updating your kernel is important if you want to take advantage of new hardware support or bleeding edge features.  Aside from these obvious benefits it also allows you to keep up with security patches, system optimization, and overall stability issues. The first thing you have to do is emerge the latest gentoo-sources package. # emerge [...]