Computer is infected. McAfee renewal is not working and completely install new virus protection on Dell Desktop computer.

The warning pop-ups and problems renewing or installing antivirus can be caused either by real malware or by fake “scareware” alerts in the browser. Use the built-in Microsoft tools to clean the system and then set up protection again.

1. Check for signs of real malware Some typical malware symptoms include:

• Unusually slow PC, frequent crashes, or not responding
• Inability to start antivirus or tools like Task Manager
• Browser home page changed and cannot be restored
• Constant unexpected pop-up windows

These symptoms may indicate malware, but they can also be caused by other issues. Because it is hard to tell, run the recommended Microsoft tools to be sure.

2. Run Microsoft Safety Scanner If McAfee is not working and other products cannot be installed, use Microsoft’s free on-demand scanner:

• Download and run Microsoft Safety Scanner from the official Microsoft site: Microsoft Safety Scanner
• Update its signatures if prompted and run a full scan
• Let it detect and remove any malware it finds

3. Use Windows Defender / Microsoft Defender Antivirus Windows 10 includes built-in antivirus (Microsoft Defender Antivirus / Windows Defender):

• Ensure McAfee is not blocking it. If McAfee is expired and not working, consider uninstalling McAfee:
  1. Go to Start > Settings > Apps
  2. Find McAfee in the list
  3. Select it and choose Uninstall
  4. Restart the PC if prompted
• After uninstalling, make sure Microsoft Defender Antivirus and Windows Firewall are turned on.

4. Remove detected threats with Windows Defender If Defender finds threats:

• Use the Clean computer option when prompted
• Defender will remove the threats and notify when finished
• To review what was found, open Defender, go to the History tab, and select All detected items

5. If malware keeps coming back If the same malware is repeatedly detected:

• Run an offline scan with Microsoft Defender Offline:
  1. Select Start > Settings > Update & Security > Windows Security > Virus & threat protection
  2. Under Current threats, select Scan options
  3. Choose Windows Defender Offline scan and select Scan now
  4. The PC will restart and scan outside of Windows to catch hidden threats

6. If the system is badly damaged If malware has caused irreversible changes and the PC remains unstable even after cleaning:

• Back up important files to an external drive or a cloud service (preferably from backups made before the infection)
• Use Windows recovery options to reset or reinstall Windows 10
• After reinstalling, immediately run Windows Update and ensure Defender is active before installing any other antivirus

7. Prevent future infections

• Keep Windows updated via Windows Update
• Keep antivirus definitions up to date
• Make sure Tamper Protection is turned on in Windows 10/11 so malware cannot easily disable security settings
• Avoid suspicious sites and downloads, especially “free” or illegal content

8. About “tags” In the forum where the question was posted, a tag is a label that identifies which product or area the question relates to (for example, “Windows for home”, “Windows 10”, “Security and privacy”). It helps route the question to the right experts.

References:

• Microsoft resources and guidance for removal of malware and viruses
• Troubleshoot problems with detecting and removing malware
• Protect my PC from viruses
• Endpoint Protection client frequently asked questions
• When you open a file on a Windows based computer, the file may start a different program