Your Boot Camp based Virtual Machine has hung in the Stopping state and keeps stopping even after Mac's restart.
- Restart your Mac.
- Start Parallels Desktop but do not start Boot Camp Virtual Machine
- In Parallels Desktop menu-bar go to Window menu -> Virtual Machines List
- Right-click on your current Boot Camp Virtual machine -> Remove -> Move to Trash
- In Parallels Desktop menu-bar go to File -> New. Create a new Virtual machine based on Boot Camp
This issue may happen if either "Safe Mode" or "Undo Disks" option has been enabled for the virtual machine. This configuration is not supported by Boot Camp based virtual machines.