I can replicate this with an identical stack trace. The madwifi driver stops working after this, which is sort of disappointing.
** Changed in: linux-source-2.6.15 (Ubuntu) Status: Unconfirmed => Confirmed -- system half-hangs after wifi scan https://launchpad.net/bugs/48642 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs