This Windows update is snarling up some endpoint security tools

Some Windows users are still feeling the fallout from apparent conflicts between recent OS updates and certain antimalware and antivirus software.

Microsoft this week said an issue involving Trellix's endpoint security software on some Windows 10 and 11 systems that installed KB5027231 and later updates, was sorted out when the cyber company issued an update to its own product.

According to a note in the Windows Health Dashboard, some users – including those running Windows Server 2022 – were unable to open Microsoft or third party software, such as Outlook and other Office programs. It only affected 32-bit apps running on 64-bit Windows running Trellix's Endpoint Security software.

"When attempting to open an affected app, Event Log indicates an access violation with the error 'module is unknown'," Microsoft wrote. "This issue is not likely to be encountered by consumers using Windows devices in their home."

The problem affected systems using Trellix's Endpoint Security Agent (HX) versions earlier than 35.31.25, Redmond wrote.

At the same time, Microsoft told users who are having problems with other security software to contact the support services of their security software providers.

That's good to note because almost immediately after the KB5027231 security update was released June 13, some Windows users reported that they were unable to access Google's Chrome browser on their systems.

It turns out the problem involved Malwarebytes and the Exploit Protection module in its security lineup, which was keeping the web browser from loading. It could be seen in the Windows Task Manager, but it wouldn't open.

When the Malwarebytes anti-exploit tool detects a shielded application that is under attack, it automatically stops the malicious code from executing.

After offering a couple of workarounds, Malwarebytes released a fix less than a week after the problems arose.

With its own repair, Trellix noted that the update to its software fixed a number of other problems unrelated to the Windows issue. Trellix was created last year after private equity firm Symphony Technology Group combined McAfee Enterprise – which it bought for $4 billion in 2021 – and FireEye, which it bought the same year for $1.2 billion.

Looking at the Start Menu and Windows Search

Microsoft has also this week fixed a problem that caused the Start Menu, Windows search, and Universal Windows Platform (UWP) applications to not work properly or not always open.

The cause of the issue is unclear but Redmond wrote that "affected Windows devices might have damaged registry keys or data which might affect apps using Microsoft Office APIs to integrate with Windows, Microsoft Office, or Microsoft Outlook or Outlook Calendar."

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The company pointed to Barco's collaboration software ClickShare as one of the affected apps. The underlying issue isn't caused by a Windows update but may arise via an update to the affected app itself.

Microsoft initially suggested uninstalling apps that integrate with Windows, Office, Outlook, or Outlook Calendar and to contact the affected software's developers.

The software giant this week said the Windows KB5027303 update released on June 27 also fixes the problem, which affects Windows 10 and 11 systems. ®