To run VNL on a 64-bit Ubuntu, you must install the "lib32g2c0" package. This can be done either via the Synaptic Package Manager (menu System>Administration) or by using the command
sudo apt-get install lib32g2c0
In addition, if you want to run a license server on Ubuntu 64-bit, see this thread (http://quantumwise.com/forum/index.php?topic=333.msg1917#msg1917).