Me too, I'm running an Averatec 3715-EH1 laptop with an internal RT2500 wireless card. Worked perfectly in Breezy, then I apt-get dist-upgraded to Dapper yesterday. Now when I 'ifup ra0' or 'dhclient ra0' the system hangs. -- Ralink Wireless USB hangs PC https://launchpad.net/bugs/34902