OLD Computer BSOD every time a network computers connects to a shared folder

Hello All;

This started happening the other day.
And since I brought a new DC into the network, I reinstalled the old DC to use as a file server only.
I thought at that time, that since the system had been up and running for 3 years, that it was time for a reinstall any way.
However, the BSOD's continued to happen.

Every time that a network computer access a share, the server reboots.
However, it does not leave a paper trail every time it reboots.
So I F8 and made it not shut down after a BSOD, and this is what I got from it.


STOP: 0xD1
ftdisk.sys - Address F740F068 base at F73F5000
acpi.sys   - Address F743E518 base at F7432000

The above BSOD caused a Dump file that pointed solely to the acpi.sys as being the issue.

I looked in on one of the earlier dump files, and it was pointing to
CLASSPNP.sys

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Things I have done.
chkdsk /f
All drives check out OK, with no known issues.

I have replaced the Network cards 4 times and it still reboots during network connection.
(I even tried the 4 NICS in each of the 3 open PCI slots, and still caused the same issue)

Example.
I am converting our music library to a smaller bitrate, and when I connect to the server
To update the MP3 Metadata
It reboots, and this is what I did to cause the above 2 Dump files.

I have removed all other PCI cards that were not being used.
And even swapped out the memory.

Anything else that anyone can think of?
Besides that, the motherboard could be going?

One last note.
As long as no network connections are made, it stays on for a long time.
The longest being about 3 hours before my son stopped by, and moved the mouse on my other computer, causing it to send a signal to the server and off she went to blackness again. (The program was opened that edits the MP3 Metadata)

Carrzkiss