T61p won't hibernate automatically anymore...

T61p running Vista ultimate fails to auto-hibernate now. It used to function before. If I force it hibernate, it does so just fine. Changing the lid close function to hibernate also works. It however will not hibernate when in sleep mode, despite setting the timers correctly.

Can anyone tell me where to start looking? First thing I did was check my LAN connections, and the WOL feature is turned off, and power saver is on.

 

OK.. this is even stranger. After running some tests, I've noticed that the computer will automatically hibernate on AC power. Switch over to battery, and the computer will not automatically hibernate. Any suggestions?

 

OK - doesn't seem many people here know how to solve this, but I do have a last question:

When the laptop is in sleep mode, do event timers such as hibernate still function if the BIOS option to ignore system events when NOT on AC power is enabled?

This is the option that comes with a warning; turning it off may allow the computer to wake for system events, and if the unit is moved while the hard drive is on may cause system damage. There is also a statement that this could void your warranty.

If so, this may explain why the system will only hibernate automatically when its connected to the adapter.

Does this theory sound plausible? Can anyone verify this?

Addendum: OK, just tested this by turning that safety feature off. Hibernate automatically kicked in. So I guess that solves that. However, this doesn't make a whole lot of sense. I would assume that most would want their laptops to automatically hibernate after a set period of time when on battery, and can afford to let the computer sleep or remain on when plugged in. By keeping this particular power option enabled in the BIOS, you're preventing the OS from doing its thing....