If the wmi queries do not deliver result for some reason, the agent doesn't properly timeout after the configured period. Instead, the agent process is hanging and no longer answering other requests. After all processes are hanging, the agent no longer responds to server requests. This was tested with system.uname, which uses wmi to get data, but the same problem happens with any wmi.* items.
With debug level 5 each of the processes write no more log entries after this