I have an extremely similar problem. I've got a Toshiba Satellite laptop with a Netgear FA510 PCMCIA wired network card. After my initial install and VL boots up and I log in for the first time, the card works fine. I can browse the web, send email, all of it. Then, once I log off and then log back in, nothing. The lights are on on the card, my router can see the card, but the computer doesn't and I have no internet access.
I'm a total noob at Linux, but generally tech-savvy, and would love some help.