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Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →When Microsoft Defender keeps popping up, start by checking Windows Security > Protection history. A repeat prompt can mean a threat still needs a decision, a potentially unwanted app is blocked but not removed, cleanup is incomplete, or Windows is reporting a protection setting—not necessarily that every new alert is an active infection.
What a repeated Windows Defender alert can mean
Protection history is the place to identify what Windows Security is reporting. Its entries can include threats awaiting a decision, blocked or quarantined items, incomplete cleanup, potentially unwanted apps (PUAs), and notices that a protection service is off. Microsoft says the history keeps events for two weeks; threat details may require administrator privileges. Microsoft Support: Protection History in the Windows Security App
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- Threat found — action needed: Defender detected a possible threat and is waiting for you to choose an action.
- Quarantined or blocked: The item has been prevented from running, but it may not have been removed. You can remove it or restore it; restoring an unsafe file can cause Defender to detect it again.
- Remediation incomplete: Defender could not finish cleaning the item. Expand the event card and follow its listed next steps.
- Potentially unwanted app: A PUA is not necessarily malware, but it may cause unexpected advertising, slow performance, or install other software. It can stay blocked until you choose an action and select Start actions.
- Service or protection status: An entry may report that a service, such as SmartScreen for Edge, is off rather than identify a newly found file.
If an older alert is missing, it may have aged out of the two-week history. On a work or school computer, an administrator may control security settings or need to review threat details.
Check the alert and choose the right action
- Open Windows Security and select Protection history. Find the newest relevant card, expand it, and read the detection name, status, and available actions.
- If the card says an action is needed, select an action appropriate to the item. If you are unsure whether a file is safe, Microsoft advises choosing quarantine rather than allowing it. Allowing an unsafe file can put your data, personal information, or device at risk.
- For a PUA, choose an action and select Start actions. Leaving it blocked without completing that step can leave it on the device and lead to further detections.
- If cleanup is incomplete, expand the event and follow its specific instructions rather than dismissing the alert.
Microsoft’s guidance on PUAs explains the available blocking settings and action flow: Protect your PC from potentially unwanted applications.
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Run scans if unwanted software may still be present
If the alert points to unwanted software or keeps returning after you have handled the event, update Microsoft Defender security intelligence and run a full scan. Uninstall software you do not need. Microsoft also recommends a Defender Offline scan if unwanted software persists; it restarts the computer, so save open work first. After the scan, check Protection history for its results.
- In Windows Security, open Virus & threat protection and check for security intelligence updates.
- From the scan options, run a Full scan if you suspect unwanted software may be on the device.
- Uninstall software you do not recognize or no longer need, using Windows Settings’ installed-apps controls.
- If the problem persists, select Microsoft Defender Offline scan from scan options and start it after saving your work. The PC will restart.
For Microsoft’s guidance on unwanted software and scans, see Protect your PC from unwanted software and Virus and Threat Protection in the Windows Security App.
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Turn down optional notifications—not urgent warnings
If Protection history shows no unresolved threat and the pop-up is informational, adjust optional notification settings rather than turning off antivirus protection. In Windows Security, open Settings > Manage notifications to change available notification categories. Windows also lets you manage banners and notification-center display under Settings > System > Notifications. Windows Security continues to show notifications for problems that require immediate action.
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See Microsoft’s instructions for Windows Security App Settings and Notifications and Do Not Disturb in Windows.
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Do not use turning off real-time protection as the routine way to stop prompts. Files opened or downloaded while it is off will not be scanned during that period. If one trusted file or folder needs an exception, Microsoft identifies an exclusion as a narrower alternative to disabling antivirus protection; use one only when you understand the risk. If a third-party antivirus is installed, Microsoft Defender Antivirus may enter disabled mode automatically and should return to active mode when that product is uninstalled. Check protection providers in Windows Security if Defender’s status—not a detection—is what keeps appearing.
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If this is a work or school device and settings are locked, or the alert refers to managed protection, contact your organization’s IT administrator. Microsoft’s guidance on scanning an item with Windows Security covers item scans and related protection behavior.
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- FAST & CONVENIENT LOGIN: Plug in your YubiKey 5C NFC via USB and tap it, or tap it against your phone (NFC), to authenticate. No batteries, no internet connection, and no extra fees required
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- PRIMARY & SPARE KEYS: Just like having a spare house key, we recommend buying two YubiKeys - one for daily use and one as a spare. That way you’ll never get locked out of your accounts
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