unknown terminal "xterm-256color"

sudo apt-get install ncurses-term

echo "export TERM=xterm-256color" >> ~/.bashrc

echo "export set t_Co=256" >> ~/.vimrc

convert ext3 -> ext4

umount /dev/sda1

tune2fs -O extents,uninit_bg,dir_index /dev/sda1

e2fsck /dev/sda1

append to kernel boot options in file: /boot/grub/menu.lst rootfstype=ext4

force fsck

sudo touch /forcefsck

or during boot press Alt+F+F to check the filesystem