I have a Dell 5100 which is approximately 2 years old. When I switch on the mains supply there is usually a brief activation ( sounds like hard disk or fans ) & when I subsequently press the button on the front of the case the system starts up. At the moment this is not happening. There is no light showing on the keyboard, the red light that shines out from the base of the mouse does not appear. The power light shows amber on the monitor and pressing the button furthest left results in message "In power save mode, press any key on keyboard or move mouse". So far I have tried removing all connections & powering up. I have also checked for loose boards & connections inside the case. Any ideas? Is this most likely to be a hardware problem?