hold the power button for about 10 seconds. then physically unplug the computer from the wall and hold the front button for another 10 seconds. Plug it back in and see if it works.

Can you hear the BIOS beep? If no, check all your connections, specifically the CPU, RAM and display. If it does beep, does it give a quick, short single beep, or a long/repeating beep? If it's the latter, check your motherboard's manual to see what the beep you hear signifies and go from there.

As an addendum to nizzy1115's suggesion, you could also remove the BIOS battery for about an hour and then try starting the computer. This effectively clears the CMOS and resets it to default, fail safe values.

Have you found that is necessary to remove the bios battery for that long? It seems really excessive to me that the rom chip could get juice for more than a second or two. Am i wrong?

I really don't know for sure. My mobo (MSI K8N Neo 3) has a clear CMOS switch. I don't have to remove the battery, I just press the switch and voila! Instant CMOS reset. Most other boards do have jumpers for the same purpose I guess.

bios beeps happening ? maybe ur PSU doesnt have enough power and is overloaded.. wats ur wattage ?

I have the same problem with my pc....i press the power button, then it beeps very annoying....I shut down it, unlplug it, remove CMOS battery. i put it after 3-5 minutes, after that cmos deafaults are loaded....and when i will restart my pc and the same problem... the pc is beeping and continues to beep so i have to do the same thing again and again.... what you would advise me? thank you

I've had that problem at work but only when I've replaced ram with newer bigger ram. I turned the machine on afterwards and it just beeped for ages so I checked the ram and noticed I hadnt put the ram in correctly :-s so give that a check.

I need some help too if anyone can. my pc at home has a problem at the moment where when it starts up it gets to the Windows XP loading page then quickly goes to bluescreen then quickly restarts. I can never get the pc fully on, any ideas why this might be happening?

I found the solution for the problem... and it was the FSB.. adjust your FSB (for the CPU) from the CMOS panel...

Well have you tried to hold the power button for 10-15 seconds if not do that it will start...