Have you tried the open-source driver "Nouveau"? This is the only one Nvidia graphics card driver which is officially supported by DisplayLink. The official graphics driver from Nvidia is unfortunately not supported. I have opened a thread about this one (
http://displaylink.org/forum/showthread.php?t=64930) and DisplayLink is not answering on it.
I must say that the support here by DisplayLink is sparse. Good luck...