If you can`t load GNOME

error: configuration defaults for gnome pwer manager not installed correctly …

Ошибка! Настройки конфигурации по умолчанию системы управления питанием Gnome …

1. The way to avoid this problem is to keep enough disk space for the system.

2. If you already have it just do:

 ctr-alt-f1 (or f2)
 sudo apt-get autoclean
 sudo apt-get autoremove
 sudo reboot
 

First one removes local repository, the second one removes depended packages if they not needed

3. If it didn`t help then unistall some application or files you don`t need

  sudo apt-get remove something_large
  sudo rm something_large
  sudo apt-get autoremove
  sudo reboot

4. If you can`t get to the terminal, first enter your password in unworking window which you usually use to enter gnome, after that you can use step 1