XenServer VM (Guest) will not Force Shutdown

Issue
A XenServer guest will not shutdown due to a pending task. In this case, it hung while adding an adapter while the guest was running - but has happened to me on other tasks as well.

Solution

1. Attempt to cancel the task though the console.
1. Use xe task-list , which will give you a list of tasks running, along with the UUID.
2. Use xe task-cancel uuid=[task uuid] to end the task
2. Sometimes the task will not respond, in which case you need to restart the toolstack
1. Use xe-toolstack-restart to restart.