Solaris VM can't be poweroff

Thank you forgive my poor English.

It seems KVM can’t poweroff solairs 10 or sloalrs 11 VM.
I have created solaris 10 and 11 as usual. Everything in VM is running OK, but finally I use shell command ‘poweroff’ or ‘init 5’, the solaris VM (both 10 & 11) system could’t be poweroff but with promoting me the message: perss any key to reboot ….. ,I pressed any key in vnc client, solaris VM reboot immediately. Endless reboot loop above.
I doubt ACPI a little bit in KVM.

I have try the suggestion as follows, but I can’t solve the problem.
7.2 Solaris reboot all the time on grub menu
• Run through the installer as usual
• On completion and reboot, the VM will perpetually reboot. "Stop" the VM.
• Start it up again, and immediately open a vnc console and select the Safe Boot from the options screen
• When prompted if you want to try and recover the boot block, say yes
• You should now have a Bourne terminal with your existing filesystem mounted on /a
• Run /a/usr/bin/bash (my preferred shell)
• export TERM=xterm
• vi /a/boot/grub/menu.1st (editing the bootloader on your mounted filesystem), to add "kernel/unix" to the kernel options for the non-safe-mode boot. Ex :
Config File : /a/boot/grub/menu.lst
kernel$ /platform/i86pc/multiboot -B $ZFS-BOOTFS kernel/unix

According to KVM requirements, I collected the following information:
CPU model name
model name : Intel(R) Xeon(R) CPU X3450 @ 2.67GHz

kvm -version
QEMU PC emulator version 0.12.3 (qemu-kvm-0.12.3), Copyright (c) 2003-2008 Fabrice Bellard

Host kernel version
Ubuntu 10.04.1 LTS 2.6.32-25-server

What host kernel arch you are using (i386 or x86_64)
X86_64

Guest OS
Solaris 10 and Solaris 11，both can not shutdown

The qemu command line you are using to start the guest

First, I used the command line as follows:
kvm -m 1024 -drive file=solaris10.img,cache=writeback -net nic -net user -nographic -vnc :1
then I try to use -no-kvm-irqchip or -no-kvm ,but the problem also appears!

Secondly, have created and run solaris 10&11 by using Virsh, still solaris can't be poweroff, the XML file content is :
<domain type='kvm'>
    <name>solairs</name>
    <uuid>85badf15-244d-4719-a2da-8c3de064137d</uuid>
    <memory>1677721</memory>
    <currentMemory>1677721</currentMemory>
    <vcpu>1</vcpu>
    <os>
    <type arch='i686' machine='pc-0.12'>hvm</type>
      <boot dev='hd'/>
   </os>
   <features>
    <acpi/>
    <apic/>
   </features>
  <clock offset='utc'/>
   <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
   <on_crash>destroy</on_crash>
   <devices>
     <emulator>/usr/bin/kvm</emulator>
     <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2' cache='writeback'/>
       <source file='/opt/GuestOS/solaris10.img'/>
       <target dev='hda' bus='ide'/>
     </disk>
    <interface type='bridge'>
      <mac address='00:0c:29:d0:36:c3'/>
      <source bridge='br1'/>
      <target dev='vnet0'/>
     </interface>
     <input type='mouse' bus='ps2'/>
     <graphics type='vnc' port='5901' autoport='no' keymap='en-us'/>
    <video>
      <model type='vga' vram='65536' heads='1'/>
    </video>
  </devices>
  <seclabel type='dynamic' model='apparmor'>
    <label>libvirt-f36f5289-692e-6f1c-fe71-c6ed19453e2f</label>
    <imagelabel>libvirt-f36f5289-692e-6f1c-fe71-c6ed19453e2f</imagelabel>
  </seclabel>
 </domain>