Ok, I work at a computer store called simple computers, we have this computer that will always restart no matter what you select in windows (shut down, hibernate, restart) It has an MSI board, and is a few years old. This is what i have tried: -uninstall then reinstall windows -update drives -unplug power and reset switch while computer is running then turn it off I really cant think of anything else, can you???
I wonder if there's some bug with the chipset whereby it interprets all the shutdown commands as 'reboot', perhaps a BIOS flash?
Could be one a few probs, First go with the power switch, remove from m/Board....to start computer cross the switch points with the end of a smnall screw driver....try your shutdown now....still persists then may be a problem with a diode in the PSU, replace PSU. see how you go with that