I have been experiencing the same problem. I have an Apple MacBook Pro 17" and installed dapper on it. I also noticed it was network related and perhaps triggered by wpa_supplicant/knetworkmanager combo. This led me to find this thread. Unlike others, my lspci gives me slightly different numbers: 168c:001c
-- [madwifi] Semi-random system lockups in Dapper https://launchpad.net/bugs/37773 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs