Have you tried turning off "auto-tuning" on the Vista machines?
Fix Problems With Copying Large Files in Windows Vista
http://www.howtogeek.com/howto/windows-vista/fix-problems-with-copying-large-fil
es-in-windows-vista/

Signature
Merv Porter [SBS-MVP]
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> We have a group of Vista clients happily connected to our SBS 2000 server
> for
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> Thanks
> Neil
Neil - 27 Mar 2008 03:08 GMT
Merv
thanks for the quick response - sorry but your suggestion does not fix the
problem.
I have been talking to Microsoft this morning and they are investigating -
but it is beginning to look like a bug
Any other suggestions ?
Neil
> Have you tried turning off "auto-tuning" on the Vista machines?
>
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> > Thanks
> > Neil
Merv Porter [SBS-MVP] - 27 Mar 2008 12:09 GMT
No other suggestions at the moment, but I'll keep looking.

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Merv Porter [SBS-MVP]
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> Merv
>
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>> > Neil
Neil - 28 Mar 2008 07:38 GMT
Merv
problem solved : )
Reinstallation of the INTEL network driver on the Vista Client fixed the
problem
Very strange indeed - Microsoft agreed it was odd and are passing it on.
This was on 3 notebooks so is an issue - apparantly with the Intel Network
drivers not installing properly after SP1
Neil
> No other suggestions at the moment, but I'll keep looking.
>
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> >> > Thanks
> >> > Neil
Merv Porter [SBS-MVP] - 28 Mar 2008 12:08 GMT
Nice work Neil! Thanks for posting your resolution.

Signature
Merv Porter [SBS-MVP]
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> Merv
>
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>> >> > Neil