If the DCS 6.5 agent is not updating its policy on a Windows Server, then the SISIPSService may have been put into an unresponsive state due to a deadlock.
Policies will not apply to Windows Server machines and if the agent is not updated, then there is a potential for BSOD's to occur on the Windows Servers that are experiencing SISIPSDriver deadlocks.
6.5 Agent Hot Fix 9 resolved an issue where Windows Server systems could be put into an unresponsive state due to a deadlock caused by the SISIPSDriver while performing a cleanup task on its process termination.
Ensure that the DCS IPS Driver is running and loaded (SISIPSService):
If the service is running, the agent version is below "184.108.40.2068", and is not receiving policy updates then the Hot Fix 9 agent should be installed:
The agent can be downloaded HERE and upgraded on any 6.5 agents experiencing this issue.