This tends to happen if I try to restart my pc, but occasionally can happen at any time.
I have a 2 year old HP pc. When I switch it on, the fan starts, and there is an amount of noise, but no beep. Then nothing happens. If I turn it back off by holding down the button, and leave it for a few hours, it is usually ok. I get the beep and it boots up fine.
I am getting a bit worried about this, as if it goes completely I fear I will lose the hard drive.
No bios beeps. If you truly don't hear anything, either your computer's power supply, motherboard, or PC speaker is no good... I would replace your PSU first if you know anybody who has a spare to test in your system (better news) if you still have the same problem then it is likely to be your Mobo replacing that is obviously a little more complex. As for loosing your data i do not think it is your HDD, by the same token it is wise to keep all your important files/data backed up at regular intervals as you never know, your next problem may be terminal...
For now I would do as Diodorus Siculus says. Get all your data backed up just incase. It sounds like something hardware related and you say it happens from time to time? Maybe a component is overheating? I'm not very knowledgeable when it comes to system architecture (sp?) but I'm sure someone else will have an idea
It isn't the speakers because when it boots up properly I get the beep. I don't think it is the power supply because all the lights and the fan come on. And as it is intermittent I wonder how the motherboard could be faulty. If it boots up properly then the whole system works perfectly without a hitch. It is only when I press the on button that I find out whether it is going to boot up properly or not.