Communication error between on-access driver and service for a firewall IPConnect event.

Hello

I am seeing Event 577 on several Win7 clients on our domain. I've seen it on about 5 out of 30 so far. It started a few weeks ago - machines become slow or unresponsive and need to be forcibly restarted, or in some cases while they can access the Internet, the affected machines are unable to access our local intranet (SharePoint Express 2013). It is ocurring on Dell Optiplex 7010's but today's machine is a Vostro 470.

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Log Name: System
Source: SAVOnAccess
Date: 07/06/2019 10:27:34
Event ID: 577
Task Category: None
Level: Error
Keywords: Classic
User: N/A
Computer: Charlotte.htlincs.local
Description:
Communication error between on-access driver and service for a firewall IPConnect event.

Event Xml:
<Event xmlns="schemas.microsoft.com/.../event">
<System>
<Provider Name="SAVOnAccess" />
<EventID Qualifiers="57405">577</EventID>
<Level>2</Level>
<Task>0</Task>
<Keywords>0x80000000000000</Keywords>
<TimeCreated SystemTime="2019-06-07T09:27:34.344268600Z" />
<EventRecordID>408923</EventRecordID>
<Channel>System</Channel>
<Computer>Charlotte.htlincs.local</Computer>
<Security />
</System>
<EventData>
<Data>
</Data>
<Binary>00000400010000000000000041023DE0C9001C02830100C0000000000000000000000000000000009A0000C0</Binary>
</EventData>
</Event>

---------------------------------------------

577 is preceeded by 592:
Communication error between on-access driver and service for a cross-process thread creation event.

Has anyone else seen this or have any recommendations, please? When I was researching this about a week ago I saw a post that recommended disabling HIPS. I tried that but it made no difference so HIPS was re-enabled.

Cheers.

Mark