I was transporting my G4 667 in Sleep mode, stowed it in a neoprene sleeve, and apparently it is having trouble putting itself to sleep while closed -- by the time I checked on it, the processor had been on full RPM, fan blazing, and the book was baking hot. It boots up, but it goes into Sleep mode erratically and continually. After I wake it up, it quickly jumps back into sleep. If I set energy saver settings on Never Sleep, it will still lapse into sleep but it will quickly wake itself back up, over and over... Any ideas what might be the cause of this, what I could try and replace?