how can this happen?

Hi all, I have an external 2TB raid array (Lacie Two Big). It works
fine under XP. On Vista I am getting all kinds of errors. From
IO errors to access denied errors. This is when I attach it as an
eSATA device through a SATA port that I have brought to the outside
with a bracket. The XP machine works the same way, exact same machine.

if I connect this drive under Vista as a USB drive (its SATA/USB) I dont
see any of these issues and everything works fine.

So what can cause a drive to behave differently under SATA than under USB?
Bug in the BIOS? Bug in the sata driver?

Any help is appreciated,

Cor