During both an upgrade install (from 8.04 on a Dell x100) and a fresh install (on a Dell D600), my wireless networking vanished. There may be several solutions for this, but the one that has worked for me (so far) is the one I found on the UbuntuForum, by Moly. I haven't tried something similar on my Macbook ... yet ...
Re: kwlan disabled my eth0 and eth1 ports; how to reenable?
http://ubuntuforums.org/showthread.php?t=96538
Moly reports
I seem to have fixed it. I went to /etc/network/interfaces and found Code:
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto eth0
#iface eth0 inet dhcp
So I uncommented out the last line, and added Code:
# The wireless network interface
auto eth1
iface eth1 inet dhcp
and then I restarted the network with Code:
/etc/init.d/networking restart
