Today I was facing and error with monitoring agentless servers. The agent proxy was getting access denied to event logs. In my environment the health services run under the local system account.
I added the server account to administrators on the agentless server but it did not help.
Then I made changes in the default action account profile for the server and and specified another action account instead of the local system action account to run the healthservices under.
Then everything was peachy...