Tente isto:
Abra um terminal
Pressione Ctrl + Alt + T
Execute:
$ sudo -i
# OLDCONF=$(dpkg -l|grep "^rc"|awk '{print $2}')
# CURKERNEL=$(uname -r|sed 's/-*[a-z]//g'|sed 's/-386//g')
# LINUXPKG="linux-(image|headers|ubuntu-modules|restricted-modules)"
# METALINUXPKG="linux-(image|headers|restricted-modules)-(generic|i386|server|common|rt|xen)"
# OLDKERNELS=$(dpkg -l|awk '{print $2}'|grep -E $LINUXPKG |grep -vE $METALINUXPKG|grep -v $CURKERNEL)
# apt-get clean
# apt-get remove --purge $OLDCONF
# apt-get remove --purge $OLDKERNELS
# rm -rf /home/*/.local/share/Trash/*/** &> /dev/null
# rm -rf /root/.local/share/Trash/*/** &> /dev/null