The Toshiba Desktop Replacment 17" model P35-S606 mentioned turns off with no warning. The computer will stay running longer if not connected to the AC outlet. Often will shut down as soon as a minute or as long as 1/2 hour when connected to an AC outlet. It Typically runs longer up toward the 30 minute when good ventillation is provided. Were sure the battery is not just dying because it is plugged into the wall. Often when we do charge up the battery completely the laptop will break its 30 minute record attained when plugged in. When the button is pushed after it fails it will turn right back on again. The Operating system is Xp, it has a pentium four mobile processor running at over 3 Ghz. Our question is what trouble shooting steps would you recommend to discover why this laptop is failing.