I'm running Mandriva 2006 on a desktop machine with the Madwifi drivers and a Netgear wg311t card. I had almost the EXACT same problem that CragStar had in this thread:
Likewise I found a newer version of wpa_supplicant amongst the cooker rpms (version 5.0 though, not 4.5), and after installing THAT I can now connect to my router using wpa_supplicant (passing all the appropriate parameters) at the command prompt.
This hasn't completely solved my problem however. Even though I can now connect, the connection periodically drops (usually after a couple hours) and the ONLY way to reconnect it is to go to command line and execute the above command again. Trying to connect through the gui (right click the taskbar icon, manage wireless networks, and click the connect button) does nothing. The machine will also not automatically connect when booting, I have to go to the command prompt then as well.
Without using WPA encryption, the machine connects just fine all without intervention from me and the connection stays stable for days.
Anyone had a similar experience? /var/log/messages and dmesg aren't really telling me anything useful. Any suggestions as to where else I can look?