Windows 11 Update Bugs Cause Mouse Pointer Issues and False Security Warnings

Microsoft has acknowledged two issues affecting Windows 11 users following recent updates. The first issue relates to the cumulative update KB5120998 (OS Build 26100.9278), which has caused custom mouse pointer schemes to be overwritten upon restart or system boot. Users have reported that their custom cursor settings, including animated pointers and high-DPI mouse cursors, are being replaced with oversized standard white pointers.

Microsoft is investigating the cause of this regression, which specifically impacts devices running Windows 11 builds updated with KB5120998 (OS Build 26100.9278 and later). The issue has also led to attempts to restore custom mouse themes failing, as the system immediately reverts to standard settings.

In addition to the cursor regression, Microsoft confirmed a separate notification glitch tied to recent security definition packages. Users have reported receiving pop-up warnings claiming that 'Microsoft Defender Antivirus is turned off,' despite real-time protection being active and fully functional inside the Windows Security panel.

Microsoft has assured users that their system's real-time security scanning remains fully operational in the background, and the warning is entirely a cosmetic error. The issue affects multiple versions of Windows 11, Windows 10, and Windows Server running the latest Defender updates.