Help Troubleshooting a Failure to Boot

Greetings and a good day to all y'all! I've come to humbly ask for some assistance with troubleshooting a problem with my friend's computer.

Firstly let me go over his specs:

Make/Model: Asus - Essentio CM5570-AP006
OS: Windows Vista
CPU: Core 2 Quad Q8200 - 2.33 GHz
RAM: 6GB DDR2
HDD: 750GB SATA 7200rpm
Video Card: Geforce G100 512MB

All other specs for his system can be found HERE

So the basic problem is that this computer will not boot properly. My friend has gone into further detail about what happens when he attempts to boot, and this is what he has told me:

1. He presses the power button and the computer begins to boot.
2. It goes through the usual screens until it comes to the Vista loading screen (where only the loading bar is visible).
3. At which point his fans begin to slow "waaay down", a blue screen with lots of text on it flashes for half a second then with a "beoop" his computer shuts off.
4. After shutting off, the computer will restart on its own and take him to the "There was a problem booting, what boot mode would you like to start in" screen.
5. My friend has tried booting in both normal mode, safe mode, and possibly some others but to no avail. After choosing his boot mode it will try and fail again, only to restart and repeat the process again and again.

So there you have it peoples, I have had troubles such as these in the past, however, I'm not really savvy on what kind of failure causes this kind of booting problem. I propose that it may be some sort of hardware failure, such as the PSU or something, but I'm unsure. So if anyone could offer some sage advice as to the nature of the problem and how to address it, my friend and I would be much obliged!

Thanks again!