A new bug in Windows 11 is causing some serious headaches for some PC owners, and Samsung laptop users appear to be bearing the brunt of it. Microsoft has confirmed reports that certain devices running current Windows 11 builds may suddenly lose access to the system drive after installing a February 2026 security update.
When the problem occurs, users see the “C: is inaccessible – access denied” error message, effectively locking them out of the drive where Windows and most applications reside. The company says it is actively investigating the issue and working with Samsung to determine the root cause. However, for affected users, the issue may render their machines partially unusable.
Why are Samsung laptops the most affected?
According to Microsoft’s Release Health documentation, the issue was primarily reported on Samsung consumer devices such as the Galaxy Book 4 series running Windows 11 versions 24H2 or 25H2. What’s more, it’s mostly seen in regions like India, Brazil, Portugal and South Korea, suggesting the bug isn’t limited to a single market.
Initial investigations suggest that the error may be related to the Samsung Share application, although Microsoft says the root cause has not yet been fully confirmed. The issue occurs after installing the February 2026 Patch Tuesday update (KB5077181), which corresponds to OS build 26100.7840. Interestingly, the error is not tied to a specific user action. Instead, it can show up during routine tasks like opening files, launching apps, or performing administrative operations. Once triggered, Windows may suddenly deny permission to the system drive and interrupt access to files and programs stored on it.
What actually happens when the error occurs?
The impact goes far beyond a simple error message. Affected systems may not be able to launch everyday software such as Outlook, Office apps, web browsers, and Windows utilities because these programs rely on files stored on the C drive. In some cases, the permission issues also prevent users from elevating their privileges, uninstalling updates, or even collecting diagnostic logs.
Some online users have suggested temporary workarounds, such as: B. manually changing file ownership permissions for the entire system drive. However, this could weaken Windows’ built-in protections and expose the system to further risks. Currently, Microsoft has not provided an official fix. The company says it is investigating the reports with Samsung and will share more information once the root cause is confirmed.
