At the first press of the power button to switch on the computer, the hard disk is not detected, BIOS says "unknown device" instead of hard disk. Then I switch off the computer by pressing the power button and turn it back on and then as if by magic, the hard-disk is detected and everything boots up and works fine.
I am forced to think that the hard-drive is bad, (I did change the hard drive cable with a new one but with no success).
This has been happening for a week and without fail, it always works the second time the computer is switched on. The switching on-off-on must occur one after the other with no or a few seconds time interval.
Why does it always work the second time?