Unable to reboot WIN 2008 R2 (Guest) on Debian KVM

shutdown works but reboot dont

i found at linux-kvm.org/page/Guest_Support_Status the guest support status

i got installed:

ii kvm 72+dfsg-5~lenny5 Full virtualization on x86 hardware ii qemu 0.9.1-10lenny1 fast processor emulator ii vgabios 0.6b-1 VGA BIOS software for the Bochs and Qemu emu

how to get windows 2008 serverr2 to reboot ?

thx