Sometimes when troubleshooting issues with an ESX host it's helpful to restart the host management agents. It's particularly recommended to try this first when rebooting the host (or pulling the plug) is the only other option. VMware has an excellent KB article on how to do this <a href="http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&amp;cmd=displayKC&amp;externalId=1003490">here</a>. The KB even includes a video showing the steps.
Caution: Make sure the VM's on the host are not set to start and stop with the host or they may be restarted when the management services restart.