This is some sort of issue with ESX, and, unfortunately, as this server is self managed, troubleshooting the OS configuration and performance issues is something that we cannot do unless you approve the billable time.
I would simply suggest you reboot the host (if you have not already), and check the vSphere / ESX error logs to see if you can find the source of the problem.
Finally, should you wish, we can re-install ESX on this server for you as time permits today, if you think that will solve the issue.