There isn't enough time to access the Windows boot menu to boot into safe mode.
Follow these steps to access the Windows boot menu:
1) Shutdown the VM
2) SSH into the HV and manually start the VM with the -p (pause) switch.
- Run: xm create /onapp/config/<DOMAIN_ID> -p
3) Open the VM's console in the Control Panel.
4) Unpause the domain.
- Run: xm unpause <DOMAIN_ID>
5) Quickly switch back to the VM's console window and spam the F8 key until the boot menu appears.