> It depends on how the drive is accessed.
> You have to access sector 262144 exactly.
> If your drive is partitionned in such a way that sector 262144
> in not the first sector of a fragment, I suspect that you won't see the problem.

Did you mean sector 268435456 rather than 262144?
(262144 = 268435456 / 1024)

Are there any other magic sectors we should test?