PC Powers Up, but no monitor/keyboard

Hello,

I'll try and give as much detail as possible for this.

I went to turn on my PC this morning. It sounded like it was powering up as normal initially, but my monitor could not detect a signal from the base unit. Also, the keyboard did not flash the caps/num lock lights as it does when its running its boot up tests. Additionally, any press of the caps/num lock keys does not do anything.

The base unit power light is on. The light that indicates that the processor is, well, processing, flashes sporadically as it would do if the PC was idling/not doing much.

The cd drive does not open when pressed.

The mouse light underneath DOES come on, indicating that power IS getting to that.

The PC is a Packard Bell, Windows Vista with an Intel 2 Quad processor. I honestly can't remember the RAM spec or the HD size.

Ideas?