Windows 7: reboot instead of shutdown

Hi, i have problem, when i push shutdown computer it shut down and after 2 seconds it turn on. What can be the problem? Hardware or system problem?

This is usually due to a newer operating system being installed on an older BIOS.

Try updating your BIOS.

i updated bios, my motherboard is asrock p43de.

Do you have any unknown devices listed in Device Manager?

Can you do the below


Right click Computer,
Properties,
Advanced tab,
Settings button (Starup and Recovery),
uncheck Automatically Restart.
Now when you shutdown see if it gives you an error message.

i tried also under windows xp and the same, my computer is shutting down and after 2-3 seconds its turning on..

I know it sounds stupid, but...

In BIOS, disable Legacy USB Support.

If no joy, re-enable and disable AHCI.

If no joy, re-enable AHCI and ignore this post.

Did you try disabling the auto restart under advanced settings? If there is a problem with AHCI or other low level drivers then your system may error, appear to be shutdown and restart.

what exactly option do you mean?

where exactly?

This done in BIOS (system setup). Check your motherboard manual for detailed instructions.

Right click Computer, Properties, Advanced tab, Settings button under Starup and Recovery, uncheck Automatically Restart.

Now when you shutdown see if it gives you an error message.