BSOD - cannot boot up

Please help. I have a Dell Computer with a Windows XP Home Edition Operating System. I bought it 2 ½ years ago.
I had some windows updates a couple of days ago, and when I restarted a blue screen came up with an error message that says An attempt was made to write to read-only memory. If the screen appears again, check and make sure any new hardware or software is properly installed.
If the problems continue, Disable or remove any new installed hardware or software. Disable BIOS memory options, Caching, shadowing. If you need to use safe mode, restart "“ F8 = Advanced Startup, Select Safe Mode.
Tech Info:
STOP: 0X000000BE (0XF74911D0, 0X09E2C121, 0XF789E408, 0X000000B)
Nvata.sys "“ address F74911D0 base at F7479000 datestamp 4536C767

I have tried all the F8 options, but it keeps coming up with the same error message.
I googled "Windows XP, not booting upâ€, and luckily found Windows BBS. I followed the instruction given by Evan to Askanison, did fixboot, fixmbr, chkdsk/r. Chkdsk /r went on to 70% then went back to 50% and froze. I could not exit to the command level. I turned off my computer, turned it back on, and booted from the CD (Windows XP Home Edition Service Pack 2) again, pressed R (for Repair/Recovery Console). However, it does not go to the command level, it reboots and comes up with the same error message that I have been getting before.
I managed to bring up the Dell Diagnostics "“ system tree: ran the Cannot Boot the OS tests "“ everything passed (except when it is Not Applicable), ran the system shuts down or reboots unexpectedly "“ all tests passed, ran the problems with memory "“ all tests passed.
I tried booting up again "“ no luck, the blue screen comes up, this time with the message PAGE_FAULT_IN_NONPAGED_AREA, STOP: 0x00000050 (0x9927D794, 0x00000001, 0x80536DDC, 0x00000000)
Tried booting up once again on safe mode, and the "attempt to write to read-only memory" (see 2nd paragraph above) error message came up.

I am stuck and don’t know what to do "“ please help. And thank you so much in advance for helping me.

 

It is booting past the CD and going on to boot to the HDD. The HDD is giving the error message. Booting to the Windows CD should not throw up a blue screen (that I know of). Are you watching for the screen "Press any key to boot to CD... "?

Look at how you are booting to the Windows CD. You shouldn't get blue screens if you are booting to the CD.

I am not familiar with the advice you are following.

If you are stuck without a backup, you can take the HDD out and connect it into another computer to back up the data.

If you "crash out" of CHKDSK it could mean the system was left "disrepaired ". I leave CHKDSK to run overnight. If it seems to stall, it is probably repairing something.

Matt

 

Hi Matt,
Thank you. I'll get my data backed up first, then I'll continue with troubleshooting by following your instructions.
Until then. Thanks again.