Hi All, I have a prob with my 15" 1.5Ghz Powerbook G4. It just goes to sleep randomly when i'm using it and sometimes won't come back to life. I then have to unplug it and remove the battery to put out the sleep light and then restart it. It seems to only do this once it's been on for a little while, maybe 45 minutes or something. I have noticed that if i remove the battery and run it from the mains power only it doesn't go to sleep and runs fine. Is this a problem with the battery do you think or something else? Any help would be greatly appreciated. Thanks Tom.