I mean my MB does not sleep. I receive low battery warning and a few minutes later it turns off completely(like when you hard reset your computer) instead of going to sleep. This results in loss of all unsaved data. The MB is 5 months old and I did calibrate the battery twice when I first used it. I run it using power supply all the time but make it a point to completely drain the battery atleast once in 6 weeks. 5 weeks ago I successfully made it to go to sleep w/o any problems. This time it just turned off. I've checked thrice in last one week and it turned off every time. What could be wrong. Bad battery or something else. BTW its a 2.0 CD MB with 1.25 GB Ram and all the latest OSX updates installed.