There are two computers driving me mad in the office because when we turn them on the green lights go on and I hear the HD power but the screen is blank and nothing goes on. After turning them on and off for about 10 min, they finally start up. I´ve tried changing the ATX "power box" and pluging the PCs in other sockets but with no results. Could it be related to the fact that they are both Celerons? What can I do?