Fuck Linksys, and the USB Ethernet adaptor you rode in on.

Good evening ladies and gentlemen, meet the Linksys USB100M USB-Ethernet Adaptor.

It’s a piece of shit. But don’t take my word for it. Take the word of my angry letter which I wrote to Linksys:

Man, that thing pisses me off.

The USB10T looks more like what you want. Why didn’t you get that?

The wobbly thing is so they can make the adapter really tiny. On the presumption that people with laptops like really tiny things. I see from the website that it is indeed as I suspected a really tiny thing.
The USB100TX looks more like your thing.

It’s the same concept as the pop out X-Jack which a number PCMCIA/PCCARD type notebook modems used. The X-Jack worked, but was always far more susceptible to damage than dongle style units if the jack was physically stressed. The even higher stress that the thicker Cat-5 ethernet cable would put on a fold out jack does make it an engineering challenge. I had a chance to buy one of those new Linksys USB units on sale the other day but passed it up because of concern about it’s ruggedness.

Just return it to the retailer and tell them it’s a poorly engineered POS.

In reading the Amazon reviews it seems some people are having the same problem you did

Y’all are right, of course. I failed to do proper due dilligence. It was such a small thing that I never thought to read reviews and research which was best. Oh well. Live and learn.