cant shut down

[Rach]

Hi
I have had this problem for over a year and enough is enough. I can shut
down as normal on screen but the button on the computer wont work so I
switch off at the plug.I am sure the chap that sold me the system said I had
to down load something from somewhere any ideas.
Rachel

 

[Del]

When you try to switch off do you hold the switch in for 5 seconds or just
push it in and out