Hello,
 
Even though I've encountered many threads, which have a more or less similar content as mine, but none seem to be entirely similar. I've even tried out the solutions for most of them, however, I still find myself at the same point.
 
The nature of my problem, as the title suggests, is that every time I'm trying to boot my system, the Windows XP loading logo page comes up and after a few seconds, the system restarts itself. After disabling the "Restart If System Encounters Error" option from the menu screen available after pressing F8, I was able to discover that the BSOD actually said that my system was experiencing a "PAGE_FAULT_IN_NONPAGED_AREA" problem. Thereof, I've tried to fix the problem using the following methods,
 
1 -> Taking out my RAM chips and remounting them on the motherboard.
2 -> Running Windows Memory Diagnostic tool (Both Standard as well as the Extended Test suites): Neither detected any errors with my motherboard or the RAM chips.
3 -> Tried starting using the "Last Working Configuration" option from the F8 menu: System still reboots at the same point.
4 -> Tried starting in Safe Mode: System still reboots at the same point.
5 -> Ran CHKDSK /R using Windows Recovery Console: Doesn't fix anything
6 -> Tried Repairing my Windows XP installation, it does all the things but right before it steps into the Repairing Menu, the system restarts.  
7 -> I haven't installed *any* hardware or software of late. The last *wrong* thing I did, was to shut down my system forcibly (shutting off the power directly), because it wasn't shutting down even after nearly 30 mins had elapsed since I ran the command to shut it down.
 
My last option remains, that I go for a complete reinstall of XP. However, I'm not entirely convinced that this can be the only solution and considering the overheads of taking backups, I'm not really enthusiastic about it either. I'm also hoping that I can get my hands on a different set of RAM chips to check my hardware for sure, but that'll take a week or so.
 
Can anyone guide me to a solution, which might be worth trying out before I give in? I hope that the "PAGE_FAULT_IN_NONPAGED_AREA" is quite a specific problem and can be solved without any elaborate overheads.
 
Thanks for any help!!

If your system is overclocked, set to defaults.  Try running on one stick of memory if you can. Try each stick byitself.  Double check that your heatsink is on the cpu correctly.
Try a reinstall on another hard drive to see if problem continues.
If all else fails it looks like a reformat and clean install is in order.  

1 -> I don't recall over-clocking my system ever, but however, how do I check whether it is over-clocked or not? (Do pardon my ignorance about this, but the curiosity never arose in me to do any such thing)
2 -> I've checked the RAM chips one at a time too.
3 -> The fan of processor seems to be doing a good job. Can you tell me where exactly should I be checking for the heat sink? Is it underneath the fan or somewhere around that place?

The best way to set the BIOS to the default is to clear the CMOS, directions will be in the mobo manual.  Also, try a different PSU.  Finally, run the diagnostic/repair software from the hdd mfg website off a floppy.  If these don't work, post the specs.

I'll check on the "Clearing of the CMOS" later tonight, And yes, I have tried an alternate PSU as well as running a comprehensive suite of Diagnostic tests on my hardware for a considerable duration of time.
 
At the MSDN site, I found an article about  PAGE_FAULT_IN_NONPAGED_AREA [http://msdn2.microsoft.com/en-us/library/ms793437.aspx]
 
Of all the things suggested, I think, the only viable causes left in my case are: A Faulty System Service, an antivirus software problem, or, a corrupted NTFS volume problem
 
I've run CHKDSK and verified that the last isn't my case.  
Now with Services, since my system doesn't even boot up, my only alternative is to go through the Recovery Console of Windows and try out LSTSRVC and then disabling them. The problem is that, LSTSRVC lists so many services (Auto, System, Manual, and, Boot). Now, which all services do I disable?
 
Also, w.r.t the Antivirus, how do I disable it from the Recovery Console? Delete all its files from the installation directory?
 
My system spec is:
2.4GHz Pentium 4
Intel 845G Chipset
1GB DDR400
ATI Radeon 9800 Pro (256MB) --> AGP version
Compaq Evo 510CMT  
Creative 5.1
Windows XP Home
 
All of the mounted hardware components have been in place for more than a year now. So it's not really a case of me adding a new h/w component and it konking out.  
The last s/w I installed -> uTorrent
The last game I installed -> Crysis
Antivirus I run -> AOL Anti Virus Shield
To uninstall them, would deleting the contents of their installation folders suffice?

I say your psu is not stable as g-paw mentioned. or boot up in safe mode and disabe restart on errors system properties,advanced,boot options, uncheck restart on errors

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WAITING FOR THE NEXT MOMENT TO STRIKE

 

Oh well,
I finally did a clean re-installation of XP and everything seems to be back in place. Just that I had to go through the perilous task of installing all my drivers yet again (and weirdly, my sound card isn't being recognized so perhaps I'll need to re-mount it).
 
Anyways, my point is: The PSU clearly wasn't the source of my troubles. And neither were any of the "BOOT" services. So I guess it might be corrupted irrecoverable sectors on my drive which just HAD to be formatted. Nonetheless, all your help had been encouraging and I hope this thread may help provide a source of information to others facing similar troubles. (Also hope that people can get things fixed before it all boils down to a clean re-install).
 
Cheers!