Intermittent DHCP problem

[Steve <stevepdrake googlemail com>]

Hello,

I have an irritating issue with my laptop connecting to my AP at home.
It's an intermittent problem as sometimes it connects fine, whereas
other times it won't connect at all, until I either reboot or reload the
wireless card's driver. I have tried both Broadcom and Atheros cards
with the latest stable firmware/driver versions on Ubuntu 7.04 and on
Fedora 7.

Symptoms:
I have the WPA-PSK key stored in the gnome-keyring from previous
connections, however when I attempt to connect I get one green light,
then it times out and asks for a new password.

I have examined the log files and can see that it associates fine and
the 4 way handshake completes ok. The problem seems to be that DHCP
times out. I have run a packet capture with Wireshark and I can see that
there are DHCP replies, but these are not being found by the DHCP client
for some reason. As I said earlier, sometimes they are found, so does
this point to a driver problem? With the Broadcom card I get CCMP:
failed to decrypt errors during this process.

Additionally, a side effect of this issue is that since I have
Avahi-autoip running, while network manager waits for a new password I
can see the Avahi services of other PCs on the network. As soon as I
click cancel the interface is disabled. Why can't I use the link-local
address when DHCP fails, without the annoying window in the background?
Clearly the key works, so surely there's no need for it to be
re-entered.

Thanks

Steve