No I haven't any similar entry !

The most surprising part in my kern.log ( which I can't succeed to attach because when it start opening location select window it freezes!) is that one :

-----------------------------------
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641774] irq 11: nobody cared (try booting with the "irqpoll" option)
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641782] Pid: 6, comm: events/0 Not tainted 2.6.28-11-generic #36-Ubuntu
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641785] Call Trace:
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641793]  [<c0500ab1>] ? printk+0x18/0x1f
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641799]  [<c017fc47>] __report_bad_irq+0x27/0x90
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641803]  [<c017fe0e>] note_interrupt+0x15e/0x1a0
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641807]  [<c017e9d9>] ? handle_IRQ_event+0x39/0x70
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641811]  [<c0180823>] handle_level_irq+0xc3/0xf0
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641816]  [<c010684e>] do_IRQ+0x7e/0xa0
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641819]  [<c01051f3>] common_interrupt+0x23/0x30
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641823]  [<c017e9b6>] ? handle_IRQ_event+0x16/0x70
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641827]  [<c01807d4>] handle_level_irq+0x74/0xf0
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641830]  [<c010684e>] do_IRQ+0x7e/0xa0
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641835]  [<c0127c7d>] ? update_curr+0x8d/0x1e0
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641838]  [<c01051f3>] common_interrupt+0x23/0x30
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641842]  [<c012007b>] ? hpet_rtc_timer_init+0xfb/0x100
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641847]  [<c0502d4d>] ? _spin_unlock_irqrestore+0x1d/0x40
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641855]  [<e0900a5c>] set_phy_reg+0x7c/0xc0 [ohci1394]
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641860]  [<e090099b>] ? get_phy_reg+0x7b/0xc0 [ohci1394]
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641880]  [<e08bcf5d>] ? csr1212_fill_cache+0xdd/0x160 [ieee1394]
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641891]  [<e08b5640>] ? delayed_reset_bus+0x0/0xd0 [ieee1394]
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641896]  [<e090128e>] ohci_devctl+0x14e/0x200 [ohci1394]
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641908]  [<e08b3019>] hpsb_reset_bus+0x19/0x20 [ieee1394]
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641918]  [<e08b56d3>] delayed_reset_bus+0x93/0xd0 [ieee1394]
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641923]  [<c014af4d>] run_workqueue+0x8d/0x150
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641927]  [<c014eeaa>] ? prepare_to_wait+0x3a/0x70
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641931]  [<c014b1c8>] worker_thread+0x88/0xf0
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641934]  [<c014ec50>] ? autoremove_wake_function+0x0/0x50
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641938]  [<c014b140>] ? worker_thread+0x0/0xf0
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641941]  [<c014e8ac>] kthread+0x3c/0x70
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641945]  [<c014e870>] ? kthread+0x0/0x70
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641948]  [<c0105477>] kernel_thread_helper+0x7/0x10
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641950] handlers:
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641952] [<c03b6dc0>] (usb_hcd_irq+0x0/0x90)
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641958] [<c03b6dc0>] (usb_hcd_irq+0x0/0x90)
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641961] [<c03b6dc0>] (usb_hcd_irq+0x0/0x90)
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641965] [<e08863b0>] (sky2_intr+0x0/0x60 [sky2])
Mar 23 16:12:08 MadPrt-010909 kernel: [    5.641975] Disabling IRQ #11
------------------------------------------------------------------------

But have a look on this :
this is at a time of hard reboot after freezing, some pb with skype and another segfault in qtcore
and then you can see a normal reboot.
Well I think It could be linked with qtcore because Its often happens when manipulating applications.

Mar 23 15:59:21 MadPrt-010909 kernel: [  247.670633] process `skype' is using obsolete setsockopt SO_BSDCOMPAT
Mar 23 16:10:35 MadPrt-010909 kernel: [  921.661361] kwalletmanager[3215]: segfault at 0 ip b674a840 sp bfc4bd10 error 4 in libQtCore.so.4.5.0[b65e0000+238000]
Mar 23 16:12:08 MadPrt-010909 kernel: Inspecting /boot/System.map-2.6.28-11-generic
Mar 23 16:12:08 MadPrt-010909 kernel: Cannot find map file.
Mar 23 16:12:08 MadPrt-010909 kernel: Loaded 54935 symbols from 56 modules.
Mar 23 16:12:08 MadPrt-010909 kernel: [    0.000000] BIOS EBDA/lowmem at: 0009fc00/0009fc00
Mar 23 16:12:08 MadPrt-010909 kernel: [    0.000000] Initializing cgroup subsys cpuset
Mar 23 16:12:08 MadPrt-010909 kernel: [    0.000000] Initializing cgroup subsys cpu
Mar 23 16:12:08 MadPrt-010909 kernel: [    0.000000] Linux version 2.6.28-11-generic (buildd@rothera) (gcc version 4.3.3 (Ubuntu 4.3.3-5ubuntu4) ) #36-Ubuntu SMP Fri Mar 20 19:40:40 UTC 2009 (Ubuntu 2.6.28-11.36-generic)