KERNEL_DATA_INPAGE_ERROR, atapi.sys and 0X0000007A

Hi,

I am hoping somebody might be able to advise me on what might be causing my computer not to work.

A few weeks ago my computer crashed and I got a blue screen with a STOP
error. I didn't have time to take it down. When it restarted I just got
a black screen giving me 2 options. One was to try booting again. The
second was to go to Setup. In setup, it had Unknown Device next to the
hard disk drive sections.

I tried my computer again the next day and it worked ok for many hours, until the same thing happened again.

The next day it was working again so I ran some diagnostics on my hard
disk drive. I have a Western Digital Caviar WD2500JB hard disk drive
that I bought 13 months ago, following a similar problem. I ran the
Western Digital Diagnostic tools in Windows and it passed all the tests
ok.

A few hours later it crashed again. I took out the memory, dusted it
down, then put it back in. My computer worked ok again. So I ran some
diagnostics on the memory using the memtest86 program. It passed those
tests as well.

Here are a couple of errors that I found in the system log

---
"Error code 0000007a, parameter1 c03e66b0, parameter2 c000000e, parameter3 f99ac130, parameter4 03b7d860."
---

I'm not sure if this next one lines up exactly with when a crash happened.

---
The driver detected a controller error on \Device\Harddisk1\D.
---

I downloaded the driver for the chipset from Dell's site, but it
wouldn't install because it said that my operating system (XP) already
has everything needed...

The next day I had the problem again. After a few hours it seemed to
start working again... it then seemed fairly stable. I bought some new
memory anyway, just in case it was memory related. It stayed stable for
3 weeks, until today. It crashed again.

Just before then, it had started to complain about being low on virtual
memory... then it crashed... this time I was able to get the blue
screen information, which I am going to try to include here as an image:




In case that image doesn't show, it says: KERNEL_DATA_INPAGE_ERROR

and gives the following STOP error:

STOP: 0x0000007a 0xc03E12B0, 0xC000000E, 0xF84Ac384, 0x1a12D860

I tried booting without the CD or DVD drive connected, but I got the
same error. I unplugged each component and then plugged hem back in
snugly. I still get the same error.

I then tried a hard disk from an identical PC in my computer and that
didn't work. I tried my hard disk in that other PC and that worked ok.
So I know the problem is not with the hard disk.

Somebody suggested that it might be a problem with the motherboard or
hard disk controller... but I'm afraid I don't know anything about
those... How do I know which is malfunctioning?

I am presently unable to boot up the computer. I just get a black dos
screen with an option to reboot or go to setup. In setup it still says
"unknown device" for the hard disk.

I am running Windows XP SP2 on a Dell Dimension 4300 with 512MB RAM. My hard disk is Western Digital Caviar WD2500JB.

How do I find out specifically what might be causing this problem? Thank you in advance for your advice.