why dose my computer shuts stale and on when i dont want it too please aid!?

why dose my computer shuts stale and on when i dont want it too please aid!?

do this right clikc on My computer >properties>advanced>starup and repossession >settings...now uncheck "automatically restart"..done bye

2- check the plug at the rear

3-it may be possible the button of "shutdown" is defacted and whne u press it ..it remains press...try soother button so that it comes out after press ing it...none other cause
Return it. If its matured, then its time to find a new workstation.