Same problem here , here is some info :

up-to-date ubuntu 8.10

Linux user-laptop 2.6.27-11-generic #1 SMP Thu Jan 29 19:24:39 UTC 2009 i686 GNU/Linux

 removing the modules seems to lead to this  :

[  186.805113] ------------[ cut here ]------------
[  186.805143] WARNING: at /build/buildd/linux-2.6.27/net/sched/sch_generic.c:219 dev_watchdog+0x21a/0x230()
[  186.805157] NETDEV WATCHDOG: eth0 (r8169): transmit timed out
[  186.805167] Modules linked in: ipv6 af_packet i915 drm binfmt_misc sco bridge stp bnep rfcomm l2cap bluetooth ppdev acpi_cpufreq cpufreq_conservative cpufreq_ondemand cpufreq_userspace cpufreq_stats freq_table cpufreq_powersave wmi container pci_slot sbs sbshc iptable_filter ip_tables x_tables nls_iso8859_1 nls_cp437 vfat fat parport_pc lp parport joydev snd_hda_intel snd_pcm_oss snd_mixer_oss snd_pcm uvcvideo compat_ioctl32 videodev v4l1_compat snd_seq_dummy evdev video output snd_seq_oss snd_seq_midi snd_rawmidi serio_raw psmouse snd_seq_midi_event ath_pci snd_seq wlan ath_hal(P) snd_timer snd_seq_device battery button ac snd pcspkr iTCO_wdt iTCO_vendor_support soundcore intel_agp snd_page_alloc agpgart shpchp pci_hotplug ext3 jbd mbcache sd_mod crc_t10dif ata_piix sg pata_acpi usb_storage libusual usbhid hid ata_generic ahci libata scsi_mod dock ehci_hcd r8169 mii uhci_hcd usbcore thermal processor fan fbcon tileblit font bitblit softcursor fuse
[  186.805488] Pid: 0, comm: swapper Tainted: P          2.6.27-11-generic #1
[  186.805501]  [<c0131e15>] warn_slowpath+0x65/0x90
[  186.805523]  [<c0240030>] ? get_request+0xc0/0x360
[  186.805542]  [<c012990d>] ? find_busiest_group+0x15d/0x7c0
[  186.805560]  [<c0121007>] ? enqueue_task+0x57/0x70
[  186.805578]  [<c012a28e>] ? resched_task+0x1e/0x70
[  186.805595]  [<c024d8d5>] ? __next_cpu+0x15/0x30
[  186.805611]  [<c012990d>] ? find_busiest_group+0x15d/0x7c0
[  186.805629]  [<c0118e38>] ? read_hpet+0x8/0x20
[  186.805645]  [<c014e6eb>] ? getnstimeofday+0x4b/0x100
[  186.805664]  [<c0136a26>] ? set_normalized_timespec+0x16/0x90
[  186.805682]  [<c0154437>] ? timer_stats_update_stats+0x17/0x250
[  186.805699]  [<c0254a19>] ? strlen+0x9/0x20
[  186.805716]  [<c0252a9d>] ? strlcpy+0x1d/0x60
[  186.805732]  [<c02f16a7>] ? netdev_drivername+0x37/0x40
[  186.805749]  [<c03068aa>] dev_watchdog+0x21a/0x230
[  186.805765]  [<c0130039>] ? dup_mmap+0x49/0x290
[  186.805782]  [<c0151d34>] ? clockevents_program_event+0x14/0x150
[  186.805800]  [<c014b84e>] ? ktime_get+0x1e/0x40
[  186.805816]  [<c013c038>] run_timer_softirq+0x138/0x210
[  186.805833]  [<c0306690>] ? dev_watchdog+0x0/0x230
[  186.805850]  [<c0306690>] ? dev_watchdog+0x0/0x230
[  186.805867]  [<c0137732>] __do_softirq+0x92/0x120
[  186.805882]  [<c013781d>] do_softirq+0x5d/0x60
[  186.805896]  [<c0137995>] irq_exit+0x55/0x90
[  186.805909]  [<c0113f8d>] smp_apic_timer_interrupt+0x5d/0x90
[  186.805927]  [<c01050f8>] apic_timer_interrupt+0x28/0x30
[  186.805944]  [<c01700d8>] ? __audit_ipc_set_perm+0x28/0x80
[  186.805985]  [<f8860800>] ? acpi_idle_enter_bm+0x268/0x2b7 [processor]
[  186.806033]  [<c02dcc2b>] cpuidle_idle_call+0x7b/0xd0
[  186.806049]  [<c010288d>] cpu_idle+0x7d/0x140
[  186.806063]  [<c037b471>] start_secondary+0x9d/0xcc
[  186.806082]  =======================
[  186.806091] ---[ end trace 5064be89e11c2847 ]---


01:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8101E/RTL8102E PCI Express Fast Ethernet controller (rev ff) (prog-if ff)
	!!! Unknown header type 7f
	Kernel modules: r8169


Thanks for any help