- Status: Confirmed by community reports; no official Microsoft advisory yet.
- Affected: Windows 11 preview build, delivered via update KB5120998.
- Issues: Broken mouse settings and Windows Security (Defender) false alerts.
Windows 11 users are beginning to regret that “Restart now” prompt. Two separate problems are floating around after a recent preview update, and both touch everyday features you rely on: pointing, clicking, and knowing your antivirus is actually running.
According to reports gathered by Neowin, the update KB5120998 has left some users with corrupted mouse settings, while a second bug is flooding Windows Security with false alerts that claim antivirus protection is switched off. Here is what changed, who it affects, and what you can do about it.
#1 Windows 11 mouse settings broken after KB5120998
The first complaint is straightforward: after installing the preview update, people say their Windows 11 mouse settings are broken. The Mouse & touchpad settings page, which normally lets you tweak pointer speed, scroll direction, and button mapping, is reportedly misbehaving or reverting to odd defaults.
What exactly is broken varies from user to user. Some report that pointer sensitivity resets to jarring values, others say the scroll direction flips, and a few describe buttons or gestures that no longer respond the way they were configured. The common thread is that personalization you set up over time gets scrambled or lost.
In practice, this means your cursor can feel sluggish or twitchy, or your mouse buttons stop doing what you told them to. For someone who has spent hours configuring accessibility or productivity settings, watching those options reset is more than a minor annoyance—it erases the setup you lean on.
Because this arrives through a preview build, it is worth noting that these updates are still in testing. Microsoft ships them to Insider channels and early adopters precisely so that bugs like this surface before the stable release, but that does not make the experience any less frustrating for whoever installed it first.
#2 Windows Security false alerts about antivirus protection
The second problem is arguably more unnerving, since it targets the tool you depend on for peace of mind. A separate bug is triggering Windows Security notifications that claim antivirus protection is disabled—even when it is running normally.
Users report seeing alerts that read like a “the sky is falling” warning, telling them their device is at risk or that Defender has gone quiet. The irony is that the protection is still active behind the scenes; the alert is just a false alarm firing in your face repeatedly.
The impact is less about actual exposure and more about confusion and notification fatigue. Getting pinged that your antivirus is off when it is on undermines trust in the security center, and constant pings can prompt someone to toggle settings they do not need to touch.
This kind of false “protection off” warning has surfaced in Windows 11 builds before, so it is not entirely novel. But seeing it ride along with the mouse-settings breakage is what is making this particular update a one-two punch.
What This Means for You
For most Windows 11 users, the takeaway is that you are likely fine if you are on a stable release and only touched the preview build. Preview updates roll out to Windows Insider members and early testing channels, so the affected population is narrower than a full rollout.
Still, if you installed this build, expect some setup work. You may need to reconfigure your mouse and touchpad options, and you should not panic over the Defender alerts—those are noise, not a real sign that your protection dropped.
Enterprise admins managing a fleet should be aware that this is a preview-stage issue. If you have not yet staged KB5120998 on your machines, it may be worth holding and watching for an official Microsoft Learn or support page before pushing it broadly.
How to Get It and What to Do
If you are running the affected preview build, the most practical step is to reapply your mouse and touchpad settings through the Settings app once the glitch settles. Open Settings > Bluetooth & devices > Mouse and re-check pointer speed, scroll direction, and button assignments.
For the Defender false alerts, do not toggle your protection on and off in a panic. Instead, open Windows Security and confirm the “Virus & threat protection” tile is green. If it is, the alert is the bug, not the reality—just dismiss it and wait for a fix.
Keep an eye on official channels for a resolution. Microsoft typically posts update issues on the Windows Insider Blog and in support documents, so check there before rolling back or reinstalling. And if you are not yet on this preview build, there is no rush to jump ahead of the problem.
Source: Neowin
Over to you: If you saw these bugs, would you hold off on the preview build or push through and reconfigure your settings?
