Vista - IEEE 1394 Firewire Printer Connections

I'm experincing problems connecting Epson R800 & R2400 printers via IEEE
1394/Firewire ports under VU 64bit I've obtained the latest certified
drivers, 6.5a, and installed them, both to a current install, then as first
install on a clean build.
I've also connected them via deicated cards and via the audio cards port.
Under Xp there was no problem Printers seen.

Vista installs driver but not IEEE1394 layer driver on first install. Second
install provides the interface layer; the system recognises the printer but
will not install the printer drivers: reports as corrupt/invalid hash key.

Any ideas? I've been trying to solve this problem for the last 2 weeks!!

I asked Epson about this and received the following answer:

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Microsoft has indicated to us that at this time firewire will only work
with Vista for "input" devices (ie scanners, which import information into
Vista), but not with "output" devices (printers, which output information
on the firewire port).

For the time being, we would suggest using the printer with a USB cable
instead, as this connection type has worked with Vista in all tests. We are
requesting that more research be done for possible updates or upgrades to
Vista which would allow use of Firewire printers, however we can't tell you
when such an update might become available, or if it will be created for
this operating system. We would suggest contacting Microsoft in regards to
Firewire compatibility. In the meantime, you should be able to print via
USB without difficulty.

If you require further assistance with this particular issue, please ensure
all of our previous correspondence is contained in your reply, so we can
better track the history of this issue.

If you have a different issue, please submit another E-form via our website
(http://www.epson.com), and we will respond in a timely manner. Thank you
again for contacting Epson.

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Once I switched to USB connection, the driver immediately worked.