System reboot when use kvm-virtmanager

hi, iam using kvm with virtmanager since a while without problems (and also virtualbox) but now when i start a virtual manchine the host system reboots (virtualbox still run without problems), i dont know how to fix it. My system is an amd phenom x6 1100T, 16gb of ram (amd 1600 cas9), 1 tb wd blach edition sata3, amd HD5650 1gb ddr3, an the SO is ubuntu 12.04 64 bits.
I have to say that boot with the ubuntu 12.04 64bits live-dvd, install kvm, and try to use one of the virtual manchines and the system reboot like with my installed system, 2 weeks ago i have no problems, maybe its a hardware problem, but virtualbox and all the others programs runs ok, the only that have problems is kvm. I test the mem with memtest and in 10 passed have no erros.
i will waiting for yours response.
thanks and sorry abouy my english.
bye

 

Did you check your logs for errors?

 

No, because i dnot know in what file take a look, what file i have to check?
thks

 

in .virt-manager/virt-manager.log :

Code:

[jue, 09 ago 2012 18:58:48 virt-manager 7229] INFO (cli:71) virt-manager startup
[jue, 09 ago 2012 18:58:48 virt-manager 7229] DEBUG (virt-manager:300) Launched as: /usr/share/virt-manager/virt-manager.py
[jue, 09 ago 2012 18:58:48 virt-manager 7229] DEBUG (virt-manager:301) GTK version: (2, 24, 10)
[jue, 09 ago 2012 18:58:48 virt-manager 7229] DEBUG (virt-manager:302) virtManager import: <module 'virtManager' from '/usr/share/virt-manager/virtManager/__init__.pyc'>
[jue, 09 ago 2012 18:58:48 virt-manager 7229] DEBUG (engine:555) No inspection thread because libguestfs is too old, not available, or libvirt is not thread safe.
[jue, 09 ago 2012 18:58:48 virt-manager 7229] DEBUG (systray:138) Showing systray: False
[jue, 09 ago 2012 18:58:48 virt-manager 7229] DEBUG (engine:346) About to connect to uris ['qemu:///system']
[jue, 09 ago 2012 18:58:48 virt-manager 7229] DEBUG (manager:171) Showing manager
[jue, 09 ago 2012 18:58:48 virt-manager 7229] DEBUG (engine:471) window counter incremented to 1
[jue, 09 ago 2012 18:58:48 virt-manager 7229] DEBUG (manager:171) Showing manager
[jue, 09 ago 2012 18:58:48 virt-manager 7229] DEBUG (connection:991) Scheduling background open thread for qemu:///system
[jue, 09 ago 2012 18:58:48 virt-manager 7229] DEBUG (connection:1177) Background 'open connection' thread is running
[jue, 09 ago 2012 18:58:48 virt-manager 7229] DEBUG (connection:1227) Background open thread complete, scheduling notify
[jue, 09 ago 2012 18:58:48 virt-manager 7229] DEBUG (connection:1232) Notifying open result
[jue, 09 ago 2012 18:58:49 virt-manager 7229] DEBUG (connection:1239) qemu:///system capabilities:
<capabilities>

  <host>
    <uuid>00020003-0004-0005-0006-000700080009</uuid>
    <cpu>
      <arch>x86_64</arch>
      <model>Opteron_G3</model>
      <vendor>AMD</vendor>
      <topology sockets='1' cores='6' threads='1'/>
      <feature name='wdt'/>
      <feature name='skinit'/>
      <feature name='osvw'/>
      <feature name='3dnowprefetch'/>
      <feature name='cr8legacy'/>
      <feature name='extapic'/>
      <feature name='cmp_legacy'/>
      <feature name='3dnow'/>
      <feature name='3dnowext'/>
      <feature name='pdpe1gb'/>
      <feature name='fxsr_opt'/>
      <feature name='mmxext'/>
      <feature name='ht'/>
      <feature name='vme'/>
    </cpu>
   

in /var/log/libvirt/qemu/*.log is clean for today

 

Any idea? i still will the same problem, the only that i can add is that 1 week ago after a huge update, i try again and works, i can virtualize windows 7 and centos, i was used for 2 hours, then shutdown the centos vm ok, and when i shutdowning the windows 7 vm the system restart, and after this restart all came back to the same, i can again use kvm becauso i press play to a vm the system restart. Well i look for info but i dont find nothing similar to my problem, and maybe i think thatcan be a problem of conpatibitity of the chipset mobo (990FX) and kvm, i dont know actually.
thnks

 

Solved -- The problem was the cpu, with a fx8150 works ok, but the old cpu its fine, because on a 870 mobo works ok with kvm, i think thats was an incompatibility of the mobo and the cpu.
bye