After upgrading OS X to 10.9 Mavericks your Virtual machine is shown as "Not Responding" in Activity Monitor, though it works fine.
Parallels Product maintenance Team is working hard on fixing this issue. We suggest that you subscribe to this KB so that you will be notified of any updates we have regarding the issue.
You may continue using your Virtual Machine as this issue has no real effect on its performance.
- prl_vm_app has CPU consumption above the one reported in Task Manager of SMP Windows guest