omnibook 6000 shuts down

[mike barchers]

I have a 6000 that has shut down problems. If the laptop is shut off for awhile it will stay for about a couple minutes. Once it heats up it shut off within seconds. I've checked the fan and replaced the thermo grease and still the same problem. I'm wondeing if it could be a bad processor or power supply. It does the same thing on AC power and batteries are fully charged. Any ideas would be appreciated.