Screen freezed at "Checking battery state..." at startup of ubuntu 12.10.

1. Open "/etc/default/grub" file.
   

   $ sudo vi /etc/default/grub
   

   Edit "GRUB_CMDLINE_LINUX_DEFAULT" like this,
   

   GRUB_CMDLINE_LINUX_DEFAULT="quiet splash console=tty1"
   

2. Update grub settings.
   

   $ sudo update-grub
   

3. Reboot system.

see also: http://ubuntuforums.org/showthread.php?t=1860674
see also: http://steadyassimilation.blogspot.jp/2012/04/note-ubuntu-1204lts.html