I have downloaded driver from realtek site and do like the post: http://ubuntuforums.org/showthread.php?t=1949810 .
But everytime I plug the card, system dies.

How to do with it ?
I use 12.04 amd64.

I also try 12.10. When I boot with livecd of 12.10, the card can work. But after I install 12.10, I find the driver of 12.10 is still NOT stable, sometimes works and sometimes not.