Toshiba Libretto W100 User Manual page 82

Other
This option allows you to set what the system does when the battery power
is about to run out.
If checked, when the battery power is about to run out while the system is in
Sleep Mode, the system will automatically wake up and switch to
Hibernation Mode (Default).
This setting is only available when the Critical battery action in Windows is
set to Hibernate (Default).
If unchecked, no action is taken, even if the battery power is about to run
out while the system is in Sleep Mode.
If the battery power runs out while in Sleep Mode, any unsaved data will
be lost.
User's Manual
HW Setup
6-6