I've be using the same Farallon AAUI pod on one of my machines for over 10 years on a variety of nertworking gear, including my current where everything passes through an autonegotiating 3Com gigabit switch. The only times I did have problems was when either I used a crossover cable by accident (but you are positive you are not using that) or I messed up a crimp.

See if you can pester Ian to test it for you.