Microsoft is investigating a new issue affecting some Samsung laptops running Windows 11 after installing the February 2026 security updates, in which users lose access to their C:\ drive and are unable to launch applications.

The company says it is working with Samsung to determine whether the problem is related to the Windows updates or Samsung software installed on affected devices.

“Users might encounter the error, ‘C:\ is not accessible – Access denied’, which prevents access to files and blocks the launch of some applications including Outlook, Office apps, web browsers, system utilities and Quick Assist,” explains Microsoft.