Write protect problem

I have an ASUS M2N SLI Deluxe motherboard with an external eSATA port on the
back panel. The port is connected to a JMicron JMB36x controller enabled on
the motherboard in default IDE mode.

OS is Vista Ultimate x64.

I have a Western Digital MyBook Premium ES Edition 500GB external drive
which has both USB and eSATA connectors.

When I connect the drive using USB, all is well. Everything works as it
should.

However, when I connect using the eSATA connector, the drive becomes write
protected.

How do I remove the write protection?

I'm pretty sure this is a Vista problem, because if I boot the computer from
a Image for DOS floppy, I can write to the drive.

Help would be appreciated. I posted this problem about a week ago to both
hardware_devices and file_management, but got not replies, so I'm trying
here.
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Walter B
waltblanch[at]tampabay[dot]rr[dot]com
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