Toshiba Libretto W100 User Manual page 83

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