I have reviewed the supported OS in the EN driver, and Ubuntu is not supported, you can see the full list:
Mellanox OFED supports Ubuntu 12.04, I noticed you're using 13.04, so recommend waiting for new release.
Mellanox OFED version 2.1-3.0.0 should be released by the end of the month, can't guarantee that, it might be delayed.
Mellanox OFED is available to downloaded from Mellanox website:
Let me know if that works for you.