The few machines I had do that resulted in either or both the main board and power supply being replaced. We tried replacing the CMOS battery, resetting the CMOS values, changing those values and reloading the OS. In the end, bad board or power supply.
Bob
Having problems with the Sleep, Restart, and Shut Down functions after struggling trying to get a defective external disk drive enclosure to work.
When I use any of the above functions the computer shuts down. I cannot wake by moving or left clicking the mouse as before. The computer shuts down and will not come on with the front panel power button. Ditto for Restart.
I have to pull the power cord for about a minute before reconnecting. Then I press the power button and the computer commences to boot and windows initializes very slowly.
I restored the computer to an earlier time before using the defective external drive enclosure, but I still have the same powerup/boot symptoms.

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