persistent drive sharing??

Hi

I have two notebooks - one has vista home premium - 32 bit and the other has
vista ultimate 64 bit.

On the 32 bit machine i run some external drives - 2 maxator 500 gig drives
and one lacie 320 gig drives. These are connected to the 32 bit notebook
through a targus 7 port usb2 hub to one of the usb ports on the notebook .
I share these external drives across the two notebooks through a dlink
wireless broadband router, and normally provide full control to all users in
the shared settings.

I have found that if I unplug the targus hub, and then start the 32 bit
machine - the shared setting on the 32 bit machine from the external drives
seem to reset to 'not shared', therefore if i need to use the drives from
the 64 bit machine I need to reset the drive sharing settings on the 32 bit
machine. Basically the permissions on the 32 bit machine dont persist if the
drives are disconnected.

This doesnt occur when the 32 bit machine is only turned off and the hub is
kept plugged in - only when the targus hub is disconnected when the machine
is turned off.

Is this a common issue? I used to run these externals from a xp pro desktop
machine and never experienced these problems before - is this a USB setting
or something I am missing in the drive sharing tools?

Thanks for any assistance provided.