Hi,
Please point the Update Drivers mechanism in device manager to C:\Program Files\DisplayLink Core Software\ and enable check all subfolders.
If that doesn't help please run through this guide:
http://www.displaylink.org/forum/showthread.php?t=896
If the issue persists please attach the debug logs:
http://www.displaylink.com/support/ticket.php?id=269
Thanks,
James