According to some information on another site, which I cannot FULLY interpret, Western Digital Drives can cause corruption of files when installed on PCI/IDE controller cards.

http://leuksman.com/linux/Ultra-DMA.sgml
<sect>Problems

<sect1>The UDMA Blacklist<label id="blacklist">
<p>

The following drives are ``blacklisted''. You should <bf/not/ use UDMA with
these drives as it may cause corruption of data. To avoid this, the driver
should automatically disable DMA for these drives.

<itemize>
<item>Western Digital WDC AC11000H, AC22100H, AC32500H, AC33100H, AC31600H - all versions
<item>Western Digital WDC AC32100H revision 24.09P07
<item>Western Digital WDC AC23200L revision 21.10N21
</itemize>
My setup was working fine with a Seagate HD. I pulled it and installed a WD to copy some data/files, and afterward, I plugged back in my Seagate. My system did NOT see the Seagate, OR the WD when I tried it again. My WD is NOT listed by model number above, so there are apparently other WD's to add to the blacklist.

I did a work-around, by installing the PCI card in another slot.