left my computer 'on' overnight to find it 'off' .....

[Ron Wolpa]

I left my computer 'on' overnight to find it 'off' by the next morning.
When I booted the 1st screen was the block screen (?). This never happens usually.
As no program has been configured to close the windows after completing a task I can´t see other culprit than the op. sistem itself. But why ? I´ve left my machine 'on' several times before , so it was the next morning.
Why sometimes it happens and sometimes not ?
Thanks.

 

[Mystere]

You mean the lock screen?

Sound like your computer went into hibernation. Many laptops are configured to go into hibernation if left alone while on battery, but stay running if plugged in. Is this a laptop, and maybe the power cord was loose?

 

[Ron Wolpa]

Is this a laptop, >>>>

Nope , it is a desktop with a solid power connection.
Power failure is discarded as the led digital clock on my table , which is powered by the same line than the computer , was showing correct time by this morning (this clock is a good power failure detector , if any occurs it starts to blink)
Most intriguing is that sometimes it happens , sometimes it doesn´t.
Very odd.

 

[labeeman]

Computer power supply is more sensitive to power surges than digital clocks the clock is not a good indicator of power problems.
You will need to put the PC on a UPS.