The default settings for auto hibernation on critical low battery doesn't work on the Lenovo Ideapad S10e.
The settings are simply too low and the battery gives up before the hibernation start up.
I'm using Ubuntu Jaunty Jackalope Beta on this one but I'm sure this will go for both Hardy and Intrepid as well.
Startup gconf-editor in a shell:
Browse your way into “/app/gnome-power-manager/general” and remove the check marks for “use_profile_time” and “use_time_for_policy”. Put a check mark in “network_sleep”:
Next go browse into “/app/gnome-power-manager/thresholds” and adjust “percentage_action”, “percentage_critical” and “percentage_low”:
I've set the critical value to 10% and action value to 9%. This way there will be enough time to initiate the hibernation process before the battery dies.