Here is my problem : I installed an Intel X25-M in the optical bay location with a caddy, Snow Leopard on it. My user files are in the regular HDD in the hard disk bay. I tried to calibrate my battery multiple times, and when the battery drops I get the first message "running on low power". Then, I don't get the second warning message and when there is no more power (checked with coconut), the computer turns off instantaneously. I lose the launched softs and session data. To sum up, the computer doesn't go to hibernate mode, doesn't write informations on the disk. I try with and without smartsleep. I checked that the hibernate mode was on, while low on battery power. Any Solution guys ? **SOLUTION** : I swapped the HDD and the SSD, the SSD is now in the regular HDD bay. There is no more problem of hibernation when running on low battery. The hibernation file can only be written on the root partition, which is on the SSD, it seems mac OS X doesn't handle properly that file when the SSD is placed in the optical bay via a caddy.