Try a Debian live DVD/USB instead of Ubuntu and see if you get the same results. I have had similar problems with internal network cards that were not recognized by Kali but were recognized by Ubuntu, and it was generally because Ubuntu would automatically use restricted/closed-source drivers that Debian did not include. I'm not sure if that could be a possibility with your USB ports, but it's worth a shot.
If you get the same problem in Debian, that is a good indicator you need to search for some drivers to install. Running "lspci" can help you figure out what hardware you have.
If you don't have the same problem in Debian, I would double check that you have the latest Kali ISO (1.0.5 I believe) and maybe even re-download and burn a new copy of that (and don't forget to verify checksums). If it works in Debian, it should work in Kali.
“Nothing in this world can take the place of persistence. Talent will not; nothing is more common than unsuccessful people with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent. The slogan 'press on' has solved and always will solve the problems of the human race.”