HiI have the same kind of problem (dd and klogd taking up a lot of processor cycles). Appears almost daily. If additional info is needed, please drop me a mail. I added also some parts of my syslog. I am using the RC of intrepid. It seems to be related to the wireless module.

Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858677] bad: scheduling from the idle thread!
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858684] Pid: 0, comm: swapper Tainted: P          2.6.27-7-generic #1
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858688] 
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858689] Call Trace:
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858692]  <IRQ>  [<ffffffff8023e06d>] dequeue_task_idle+0x2d/0x40
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858705]  [<ffffffff8023c436>] dequeue_task+0x96/0xe0
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858711]  [<ffffffff8023c4d3>] deactivate_task+0x23/0x30
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858717]  [<ffffffff80500685>] thread_return+0x108/0x3c3
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858724]  [<ffffffff80500d33>] schedule_timeout+0x63/0xd0
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858732]  [<ffffffff8025a3d0>] ? process_timeout+0x0/0x10
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858739]  [<ffffffff80500d2e>] ? schedule_timeout+0x5e/0xd0
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858746]  [<ffffffff80500dbe>] schedule_timeout_uninterruptible+0x1e/0x20
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858752]  [<ffffffff8025ab85>] msleep+0x25/0x40
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858774]  [<ffffffffa0b26ca3>] iwl_scan_cancel_timeout+0x63/0xb0 [iwlcore]
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858792]  [<ffffffffa0b38031>] iwl4965_mac_update_tkip_key+0x51/0x120 [iwlagn]
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858822]  [<ffffffffa0aadcde>] ieee80211_tkip_decrypt_data+0x19e/0x230 [mac80211]
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858832]  [<ffffffff802475bd>] ? default_wake_function+0xd/0x10
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858838]  [<ffffffff8023c8ca>] ? __wake_up_common+0x5a/0x90
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858865]  [<ffffffffa0aa3929>] ieee80211_crypto_tkip_decrypt+0xd9/0x130 [mac80211]
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858893]  [<ffffffffa0ab01d8>] ieee80211_rx_h_decrypt+0x1b8/0x1d0 [mac80211]
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858920]  [<ffffffffa0ab24c8>] ieee80211_invoke_rx_handlers+0x108/0x2e0 [mac80211]
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858948]  [<ffffffffa0ab1ec9>] __ieee80211_rx_handle_packet+0x289/0x380 [mac80211]
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.858976]  [<ffffffffa0ab2786>] __ieee80211_rx+0xe6/0x200 [mac80211]
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859002]  [<ffffffffa0a9f64e>] ieee80211_tasklet_handler+0x12e/0x160 [mac80211]
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859019]  [<ffffffffa0b3b309>] ? iwl4965_irq_tasklet+0x129/0x350 [iwlagn]
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859027]  [<ffffffff802546c6>] tasklet_action+0x86/0x110
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859034]  [<ffffffff80254d8c>] __do_softirq+0x8c/0x100
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859049]  [<ffffffffa0b3b058>] ? iwl4965_isr+0x88/0x110 [iwlagn]
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859056]  [<ffffffff8021417c>] call_softirq+0x1c/0x30
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859063]  [<ffffffff80215875>] do_softirq+0x65/0xa0
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859069]  [<ffffffff80254af5>] irq_exit+0x95/0xa0
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859075]  [<ffffffff80215b1b>] do_IRQ+0x8b/0x100
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859081]  [<ffffffff80212f0e>] ret_from_intr+0x0/0x29
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859084]  <EOI>  [<ffffffffa003adc4>] ? acpi_idle_enter_simple+0x16b/0x1aa [processor]
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859116]  [<ffffffffa003adbc>] ? acpi_idle_enter_simple+0x163/0x1aa [processor]
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859123]  [<ffffffff8044bb59>] ? cpuidle_idle_call+0xb9/0x100
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859131]  [<ffffffff80210e95>] ? cpu_idle+0x75/0x110
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859137]  [<ffffffff804fd735>] ? start_secondary+0x97/0xc2
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859141] 
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859162] BUG: scheduling while atomic: swapper/0/0x00000100
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859166] Modules linked in: usbhid hid ipv6 binfmt_misc af_packet rfcomm bridge stp bnep sco l2cap vboxdrv ppdev acpi_cpufreq cpufreq_powersave cpufreq_userspace cpufreq_conservative cpufreq_ondemand cpufreq_stats freq_table container pci_slot sbs sbshc iptable_filter ip_tables x_tables sbp2 parport_pc lp parport arc4 ecb crypto_blkcipher snd_hda_intel snd_pcm_oss snd_mixer_oss iwlagn iwlcore snd_pcm snd_seq_dummy rfkill snd_seq_oss led_class snd_seq_midi sdhci_pci mac80211 sdhci iTCO_wdt snd_rawmidi compal_laptop uvcvideo cfg80211 mmc_core snd_seq_midi_event snd_seq ricoh_mmc iTCO_vendor_support compat_ioctl32 btusb snd_timer videodev serio_raw v4l1_compat snd_seq_device evdev bluetooth pcspkr psmouse nvidia(P) i2c_core snd battery video soundcore ac output wmi intel_agp snd_page_alloc button shpchp pci_hotplug ext3 jbd mbcache sd_mod sr_mod crc_t10dif cdrom sg pata_acpi ata_generic ahci ata_piix ohci1394 ieee1394 libata scsi_mod dock tg3 libphy ehci_hcd uhci_hcd usbcore th
Oct 26 15:01:35 jeroen-laptop kernel: rmal processor fan fbcon tileblit font bitblit softcursor fuse
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859340] CPU 1:
Oct 26 15:01:35 jeroen-laptop kernel: [ 8973.859344] Modules linked in: usbhid hid ipv6 binfmt_misc af_packet rfcomm bridge stp bnep sco l2cap vboxdrv ppdev acpi_cpufreq cpufreq_powersave cpufreq_userspace cpufreq_conservative cpufreq_ondemand cpufreq_stats freq_table container pci_slot sbs sbshc iptable_filter ip_tables x_tables sbp2 parport_pc lp parport arc4 ecb crypto_blkcipher snd_hda_intel snd_pcm_oss snd_mixer_oss iwlagn iwlcore snd_pcm snd_seq_dummy rfkill snd_seq_oss led_class snd_seq_midi sdhci_pci mac80211 sdhci iTCO_wdt snd_rawmidi compal_laptop uvcvideo cfg80211 mmc_core snd_seq_midi_event snd_seq ricoh_mmc iTCO_vendor_support compat_ioctl32 btusb snd_timer videodev serio_raw v4l1_compat snd_seq_device evdev bluetooth pcspkr psmouse nvidia(P) i2c_core snd battery video soundcore ac output wmi intel_agp snd_page_alloc button shpchp pci_hotplug ext3 jbd mbcache sd_mod sr_mod crc_t10dif cdrom sg pata_acpi ata_generic ahci ata_piix ohci1394 ieee1394 libata scsi_mod dock tg3 libphy ehci_hcd uhci_hcd usbcore th
Oct 26 15:01:35 jeroen-laptop kernel: rmal processor fan fbcon tileblit font bitblit softcursor fuse

After this the cycle repeats.

Cheers Jeroen