Uff! I have been trying to get Hibernate (Suspend-to-disk) option work properly with Ubuntu in my home PC, versions after versions, starting from Dapper Drake (v6.04) to the recent Karmic Koala(v9.10).

Even though the actual hibernation(meaning, dumping the memory content into the Swap partition of my disk) happens fine, my machine suddenly restarts within 3 seconds after a complete halt. I have been going crazy to even figure out the sentence to help google find what I am looking for from the net.

Finally, at 9:45pm with half sleepy eyes, I managed to find some help after going thru lines and lines of posts from various forums…that I had to add a file to my /etc/pm/conf.d and add the following line to the file

HIBERNATE_MODE=shutdown

the hibernation happens properly and my machine goes to sleep happily thereafter 🙂
Thanks to this post
PS: Folks, also please ensure that you specify where your hibernate file is present to Grub to ensure it wakes up instead of booting afresh. You have to add resume=/dev/sda5(swap partition). But I also noticed recently in my dad’s netbook, without this resume option, GRUB properly wakes up from Hibernation. God knows how!…Something to research on sometime later….Will post my findings if any 🙂