You might want to try to change the usb port which is used per device.
eg.:
usb-key on lower usb-port and usb-drive on upper usb-port
TO:
usb-key on upper usb-port and usb-drive on lower usb-port
In my experience the lower usb-port is accessed first by the asus.
I've had a swap space on a usb-key for a while, but this would only work when drive was connected to lower port and key to upper port..
(small warning though.. if the asus uses the swap extensivly, it will not have a long life. Mine died after 6 months of heavy usage (and limited write cycles on a usb-key), though, the performance gain was impressive.)
HTH