Splunk Universal Forwarder suddenly stop receiving WinHostMon event

[tlam_splunk]

Running Window Splunk v652

We find that from time to time, the UF suddenly stop sending the WinHostMon events to Splunk Indexers.
Checking the log, we find the following error
ERROR ExecProcessor - Couldn't start command ""c:\Program Files\SplunkUniversalForwarder\bin\splunk-winhostinfo.exe"": Access is denied.

[tlam_splunk]

1) Check there is any anti-virus running in the Windows

2) Check there is any firewall blocking the process

3) Upgrade to the v659 or v667. It has a fix to startup the process again.