Hi,
Are you connected through an Ethernet hub? If so please see this FAQ:
http://www.displaylink.com/support/ticket.php?id=299
If not or you're not sure please attach the output of this tool:
http://www.displaylink.com/support/ticket.php?id=269
When you reply please select "Manage Attachments" from the "Additional Options" section below.
From there select Upload and navigate to the output of the tool which will be in a folder called "DisplayLink Support Files" on your desktop.
Thanks,
James