[PLUG] Wireless (sigh)

[John Jason Jordan]

Now I've done it. The Intel 4965agn in my Thinkpad T61 has always been
flaky - sudden disconnects, especially when the signal is weak.
Supposedly Hardy will fix this, so I have been using a Netgear WG511T
borrowed from Keith instead. However, the wireless LED above the
keyboard has never come on regardless of which device I use.

There has recently been a discussion on the Thinkpad e-list that I
subscribe to about how to get the LED to work and, at the same time,
upgrade to the latest driver from Intel. I did it. The LED now works.
Yay!

And now the wireless is completely dead. 

However, I suspect there is a different problem than the driver. Some
facts:

1) The Netgear card also fails to work now. (That alone should be proof
that something else is boogered up.)

2) If I do iwlist wlan0 scan, about half the time it shows all the
networks, the rest of the time it says no networks were found. Doing
killall  NetworkManager, then restarting it, restores the scanning
ability. I can also restore it by doing modprobe -r iwl4965, then
modprobing it to restart it. But eventually iwlist scan fails again.

3) If I use kwifimanager it never sees any networks, even when iwlist
at the command line is working. If I use System > Administration >
Network, go into the Properties, gturn off roaming, and click on the
drop-down button it will display all the available networks about one
try out of 50.

4) If I do iwconfig wlan0 essid <name of network> I never fail to
connect. But that just gets me connected. I still don't have an IP
address, and nothing I have tried so far can get me an IP address.

I have concluded that my problem is that I can connect fine (although
some of the software tools seems kind of flaky), but I cannot ever get
an IP address. 

So my queries are:

1) Is there a command line tool to get an IP address from an access
point? 

2) I searched all over Ubuntu forums and failed to get a definition of
"roaming mode." Does anyone know what it is?

2) Does anyone have any other suggestions?