I've recently install Ubuntu and most things are "just work[ing]" out of the box, including wifi. However, if I close the lid on my netbook --- putting it to sleep --- when I reopen the wifi simply does not exist. Strangely, the computer still knows about wlan0, but ifup was not able to recognize it; I was able to fix that by adding wlan0 to /etc/network/interfaces/, but running ifdown wlan0 does not bring down my wifi connection when it is already up. This gives me the feeling something is wrong somewhere. How can I get wireless working when the computer wakes up?
(I recognize this description is a little vague, so I am happy to respond with terminal output as requested in the comments.)
