I've replicated this on the mainline kernel, though the stack trace is slightly different.  I imagine that's to be expected.

Apr  9 11:13:20 ubox kernel: [39032.376474] e1000 0000:00:03.0: eth0: Detected Tx Unit Hang
Apr  9 11:13:20 ubox kernel: [39032.376475]   Tx Queue             <0>
Apr  9 11:13:20 ubox kernel: [39032.376476]   TDH                  <b6>
Apr  9 11:13:20 ubox kernel: [39032.376476]   TDT                  <b8>
Apr  9 11:13:20 ubox kernel: [39032.376477]   next_to_use          <b8>
Apr  9 11:13:20 ubox kernel: [39032.376477]   next_to_clean        <b6>
Apr  9 11:13:20 ubox kernel: [39032.376478] buffer_info[next_to_clean]
Apr  9 11:13:20 ubox kernel: [39032.376478]   time_stamp           <10093bd46>
Apr  9 11:13:20 ubox kernel: [39032.376479]   next_to_watch        <b7>
Apr  9 11:13:20 ubox kernel: [39032.376479]   jiffies              <10093c096>
Apr  9 11:13:20 ubox kernel: [39032.376480]   next_to_watch.status <0>
Apr  9 11:13:22 ubox kernel: [39034.380430] e1000 0000:00:03.0: eth0: Detected Tx Unit Hang
Apr  9 11:13:22 ubox kernel: [39034.380431]   Tx Queue             <0>
Apr  9 11:13:22 ubox kernel: [39034.380432]   TDH                  <b6>
Apr  9 11:13:22 ubox kernel: [39034.380433]   TDT                  <b8>
Apr  9 11:13:22 ubox kernel: [39034.380433]   next_to_use          <b8>
Apr  9 11:13:22 ubox kernel: [39034.380434]   next_to_clean        <b6>
Apr  9 11:13:22 ubox kernel: [39034.380434] buffer_info[next_to_clean]
Apr  9 11:13:22 ubox kernel: [39034.380435]   time_stamp           <10093bd46>
Apr  9 11:13:22 ubox kernel: [39034.380435]   next_to_watch        <b7>
Apr  9 11:13:22 ubox kernel: [39034.380436]   jiffies              <10093c28b>
Apr  9 11:13:22 ubox kernel: [39034.380437]   next_to_watch.status <0>
Apr  9 11:13:24 ubox kernel: [39036.384806] e1000 0000:00:03.0: eth0: Detected Tx Unit Hang
Apr  9 11:13:24 ubox kernel: [39036.384808]   Tx Queue             <0>
Apr  9 11:13:24 ubox kernel: [39036.384808]   TDH                  <b6>
Apr  9 11:13:24 ubox kernel: [39036.384809]   TDT                  <b8>
Apr  9 11:13:24 ubox kernel: [39036.384810]   next_to_use          <b8>
Apr  9 11:13:24 ubox kernel: [39036.384810]   next_to_clean        <b6>
Apr  9 11:13:24 ubox kernel: [39036.384811] buffer_info[next_to_clean]
Apr  9 11:13:24 ubox kernel: [39036.384811]   time_stamp           <10093bd46>
Apr  9 11:13:24 ubox kernel: [39036.384812]   next_to_watch        <b7>
Apr  9 11:13:24 ubox kernel: [39036.384813]   jiffies              <10093c480>
Apr  9 11:13:24 ubox kernel: [39036.384813]   next_to_watch.status <0>
Apr  9 11:13:25 ubox kernel: [39037.318026] e1000 0000:00:03.0: eth0: Detected Tx Unit Hang
Apr  9 11:13:25 ubox kernel: [39037.318027]   Tx Queue             <0>
Apr  9 11:13:25 ubox kernel: [39037.318028]   TDH                  <b6>
Apr  9 11:13:25 ubox kernel: [39037.318029]   TDT                  <b8>
Apr  9 11:13:25 ubox kernel: [39037.318029]   next_to_use          <b8>
Apr  9 11:13:25 ubox kernel: [39037.318030]   next_to_clean        <b6>
Apr  9 11:13:25 ubox kernel: [39037.318031] buffer_info[next_to_clean]
Apr  9 11:13:25 ubox kernel: [39037.318031]   time_stamp           <10093bd46>
Apr  9 11:13:25 ubox kernel: [39037.318032]   next_to_watch        <b7>
Apr  9 11:13:25 ubox kernel: [39037.318032]   jiffies              <10093c569>
Apr  9 11:13:25 ubox kernel: [39037.318033]   next_to_watch.status <0>
Apr  9 11:13:26 ubox kernel: [39038.832137] ------------[ cut here ]------------
Apr  9 11:13:26 ubox kernel: [39038.832148] WARNING: at /home/apw/COD/linux/net/sched/sch_generic.c:256 dev_watchdog+0x26d/0x280()
Apr  9 11:13:26 ubox kernel: [39038.832151] Hardware name: VirtualBox
Apr  9 11:13:26 ubox kernel: [39038.832152] NETDEV WATCHDOG: eth0 (e1000): transmit queue 0 timed out
Apr  9 11:13:26 ubox kernel: [39038.832154] Modules linked in: nls_utf8 isofs vboxsf(O) vboxvideo(O) drm bnep rfcomm bluetooth snd_intel8x0 ppdev snd_ac97_codec ac97_bus snd_pcm snd_seq_midi snd_rawmidi snd_seq_midi_event snd_seq binfmt_misc snd_timer joydev snd_seq_device parport_pc snd vboxguest(O) soundcore snd_page_alloc mac_hid i2c_piix4 psmouse serio_raw lp parport usbhid hid e1000
Apr  9 11:13:26 ubox kernel: [39038.832179] Pid: 0, comm: swapper/0 Tainted: G           O 3.3.0-030300-generic #201203182135
Apr  9 11:13:26 ubox kernel: [39038.832181] Call Trace:
Apr  9 11:13:26 ubox kernel: [39038.832183]  <IRQ>  [<ffffffff8105196f>] warn_slowpath_common+0x7f/0xc0
Apr  9 11:13:26 ubox kernel: [39038.832191]  [<ffffffff81051a66>] warn_slowpath_fmt+0x46/0x50
Apr  9 11:13:26 ubox kernel: [39038.832194]  [<ffffffff8157a74d>] dev_watchdog+0x26d/0x280
Apr  9 11:13:26 ubox kernel: [39038.832198]  [<ffffffff8108c20c>] ? trigger_load_balance+0x6c/0x1c0
Apr  9 11:13:26 ubox kernel: [39038.832201]  [<ffffffff8106e820>] ? __queue_work+0x400/0x400
Apr  9 11:13:26 ubox kernel: [39038.832204]  [<ffffffff8157a4e0>] ? __netdev_watchdog_up+0x80/0x80
Apr  9 11:13:26 ubox kernel: [39038.832207]  [<ffffffff81061e39>] call_timer_fn+0x49/0x130
Apr  9 11:13:26 ubox kernel: [39038.832210]  [<ffffffff8157a4e0>] ? __netdev_watchdog_up+0x80/0x80
Apr  9 11:13:26 ubox kernel: [39038.832212]  [<ffffffff81062259>] run_timer_softirq+0x149/0x280
Apr  9 11:13:26 ubox kernel: [39038.832216]  [<ffffffff81320620>] ? timerqueue_add+0x60/0xb0
Apr  9 11:13:26 ubox kernel: [39038.832219]  [<ffffffff810a14d8>] ? ktime_get+0x68/0xf0
Apr  9 11:13:26 ubox kernel: [39038.832222]  [<ffffffff81058aaf>] __do_softirq+0xbf/0x200
Apr  9 11:13:26 ubox kernel: [39038.832225]  [<ffffffff81079f57>] ? hrtimer_interrupt+0x127/0x210
Apr  9 11:13:26 ubox kernel: [39038.832230]  [<ffffffff8166a19c>] call_softirq+0x1c/0x30
Apr  9 11:13:26 ubox kernel: [39038.832233]  [<ffffffff81015525>] do_softirq+0x65/0xa0
Apr  9 11:13:26 ubox kernel: [39038.832235]  [<ffffffff810588ad>] irq_exit+0xbd/0xe0
Apr  9 11:13:26 ubox kernel: [39038.832238]  [<ffffffff8166aaee>] smp_apic_timer_interrupt+0x6e/0x99
Apr  9 11:13:26 ubox kernel: [39038.832240]  [<ffffffff8166979e>] apic_timer_interrupt+0x6e/0x80
Apr  9 11:13:26 ubox kernel: [39038.832242]  <EOI>  [<ffffffff8103e016>] ? native_safe_halt+0x6/0x10
Apr  9 11:13:26 ubox kernel: [39038.832248]  [<ffffffff810e6cde>] ? rcu_idle_enter_common+0x3e/0x100
Apr  9 11:13:26 ubox kernel: [39038.832251]  [<ffffffff8101c4bd>] default_idle+0x5d/0x190
Apr  9 11:13:26 ubox kernel: [39038.832253]  [<ffffffff8101c64d>] amd_e400_idle+0x5d/0x130
Apr  9 11:13:26 ubox kernel: [39038.832256]  [<ffffffff81013198>] cpu_idle+0xd8/0x120
Apr  9 11:13:26 ubox kernel: [39038.832260]  [<ffffffff8163e402>] rest_init+0x72/0x80
Apr  9 11:13:26 ubox kernel: [39038.832263]  [<ffffffff81ce9cdb>] start_kernel+0x3bb/0x3c6
Apr  9 11:13:26 ubox kernel: [39038.832265]  [<ffffffff81ce9346>] x86_64_start_reservations+0x131/0x136
Apr  9 11:13:26 ubox kernel: [39038.832267]  [<ffffffff81ce944e>] x86_64_start_kernel+0x103/0x112
Apr  9 11:13:26 ubox kernel: [39038.832269] ---[ end trace b381a0343b7464b7 ]---
Apr  9 11:15:01 ubox CRON[3714]: (dlawson) CMD (/home/dlawson/work/ubuntu-it/wget-script.sh)
Apr  9 11:16:48 ubox kernel: [39240.753552] INFO: task kworker/0:1:11 blocked for more than 120 seconds.
Apr  9 11:16:48 ubox kernel: [39240.753556] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Apr  9 11:16:48 ubox kernel: [39240.753558] kworker/0:1     D ffffffff8180c680     0    11      2 0x00000000
Apr  9 11:16:48 ubox kernel: [39240.753563]  ffff880159187ad0 0000000000000046 ffff880159187fd8 0000000000013600
Apr  9 11:16:48 ubox kernel: [39240.753566]  ffff880159186010 0000000000013600 0000000000013600 0000000000013600
Apr  9 11:16:48 ubox kernel: [39240.753569]  ffff880159187fd8 0000000000013600 ffffffff81c0d020 ffff880159188000
Apr  9 11:16:48 ubox kernel: [39240.753571] Call Trace:
Apr  9 11:16:48 ubox kernel: [39240.753579]  [<ffffffff8165f8ff>] schedule+0x3f/0x60
Apr  9 11:16:48 ubox kernel: [39240.753593]  [<ffffffff8165db4d>] schedule_timeout+0x1fd/0x2e0
Apr  9 11:16:48 ubox kernel: [39240.753596]  [<ffffffff8108bb88>] ? load_balance+0xa8/0x4f0
Apr  9 11:16:48 ubox kernel: [39240.753599]  [<ffffffff8165f73b>] wait_for_common+0xdb/0x180
Apr  9 11:16:48 ubox kernel: [39240.753601]  [<ffffffff8108d128>] ? idle_balance+0xf8/0x150
Apr  9 11:16:48 ubox kernel: [39240.753603]  [<ffffffff81085e10>] ? try_to_wake_up+0x2d0/0x2d0
Apr  9 11:16:48 ubox kernel: [39240.753605]  [<ffffffff8166065f>] ? _raw_spin_lock_irqsave+0x2f/0x40
Apr  9 11:16:48 ubox kernel: [39240.753607]  [<ffffffff8165f8bd>] wait_for_completion+0x1d/0x20
Apr  9 11:16:48 ubox kernel: [39240.753619]  [<ffffffff8106f021>] wait_on_work+0x1a1/0x1b0
Apr  9 11:16:48 ubox kernel: [39240.753622]  [<ffffffff8106d010>] ? do_work_for_cpu+0x30/0x30
Apr  9 11:16:48 ubox kernel: [39240.753624]  [<ffffffff8106f14d>] __cancel_work_timer+0x4d/0x170
Apr  9 11:16:48 ubox kernel: [39240.753628]  [<ffffffff810dfd41>] ? synchronize_irq+0x51/0xf0
Apr  9 11:16:48 ubox kernel: [39240.753630]  [<ffffffff8106f2a0>] cancel_work_sync+0x10/0x20
Apr  9 11:16:48 ubox kernel: [39240.753643]  [<ffffffffa00009b5>] e1000_down_and_stop+0x25/0x50 [e1000]
Apr  9 11:16:48 ubox kernel: [39240.753647]  [<ffffffffa0005e2f>] e1000_down+0x14f/0x230 [e1000]
Apr  9 11:16:48 ubox kernel: [39240.753651]  [<ffffffffa0006430>] ? e1000_change_mtu+0x1c0/0x1c0 [e1000]
Apr  9 11:16:48 ubox kernel: [39240.753655]  [<ffffffffa000648c>] e1000_reset_task+0x5c/0x80 [e1000]
Apr  9 11:16:48 ubox kernel: [39240.753657]  [<ffffffff8106de0b>] process_one_work+0x12b/0x470
Apr  9 11:16:48 ubox kernel: [39240.753660]  [<ffffffff81070976>] worker_thread+0x176/0x420
Apr  9 11:16:48 ubox kernel: [39240.753662]  [<ffffffff81070800>] ? manage_workers+0x120/0x120
Apr  9 11:16:48 ubox kernel: [39240.753665]  [<ffffffff810754be>] kthread+0x9e/0xb0
Apr  9 11:16:48 ubox kernel: [39240.753668]  [<ffffffff8166a0a4>] kernel_thread_helper+0x4/0x10
Apr  9 11:16:48 ubox kernel: [39240.753670]  [<ffffffff81075420>] ? kthread_freezable_should_stop+0x70/0x70
Apr  9 11:16:48 ubox kernel: [39240.753672]  [<ffffffff8166a0a0>] ? gs_change+0x13/0x13