Try our download page for the latest drivers (currently 7.1M0)
http://www.displaylink.com/support/downloads.php
The ethernet driver is in the install package, and you can find it unpacked inside \Program Files\DisplayLink Core Software\CdcEcmDriver
If you still have problems, please follow the instructions in
http://www.displaylink.com/support/ticket.php?id=269 to provide logs and system details.