Recently out of nowhere, when I hit the button to turn my pc on, the fans start up, the pc lights turn on, but there is no beep, and the lights on my keyboard and mouse doesn't work, nor does my monitor turn on. I believe I am just missing the beep, but why? After turning the computer off enough times, it eventually works, but sometimes I may have to turn it off a dozen times to get it to work. Why does it sometimes work? What can I do to fix this?