My friend spotted a problem with htop configuration. Simply when htop was executed on two different Ubuntu distros (10.04 and 14.04) the config was reset.
After some interrogation, we have spotted that 10.04 stores htop config to ~/.htoprc, while 14.04 to ~/.config/htop/htoprc. It was enough to remove one of them and link another one as below:
rm .htoprc ln -s .config/htop/htoprc .htoprc