Hi,

Please try to comment out the "WARN_ON_ONCE"
at net/sched/sched_generic.c.

--- linux-2.6.27-rc1/net/sched/sch_generic.c.orig	2008-07-29 21:45:36.000000000 +0900
+++ linux-2.6.27-rc1/net/sched/sch_generic.c	2008-07-29 21:45:54.000000000 +0900

@@ -216,7 +216,6 @@ static void dev_watchdog(unsigned long a
 				printk(KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit timed out\n",
 				       dev->name, netdev_drivername(dev, drivername, 64));
 				dev->tx_timeout(dev);
-				WARN_ON_ONCE(1);
 			}
 			if (!mod_timer(&dev->watchdog_timer,
 				       round_jiffies(jiffies +

I should'nt be posting this, due to
having  tainted modules(madwifi), but
I figured I might as well:(below)

[ 5000.986044] NETDEV WATCHDOG: wifi0: transmit timed out
[ 5000.991959] ------------[ cut here ]------------
[ 5000.991964] WARNING: at net/sched/sch_generic.c:222 dev_watchdog+0x95/0xe7()

Best Regards
Komuro