Hi,
"May 14 16:21:36.476: vcpu-0| Your guest has entered a standby sleep state. Use the keyboard or mouse while grabbed to wake it."
It looks windows 7 going in sleep mode, after system is inactive for some time.
Go to windows 7 control panel àpower options à select the power plan & select change setting.
Select never options for Turn off the display & Put the computer to sleep