A user reports persistent system instability and potential security compromise on a Windows 11 Lenovo laptop following suspicious login activity and browser-related errors.

Key Points

• The user experienced unauthorized login attempts on their Microsoft account, followed by browser malfunctions and system errors.
• Microsoft Defender and Malwarebytes are failing to detect the issue, with Defender reporting errors related to safe mode and security intelligence updates.
• System logs indicate multiple application crashes, including UDClientService.exe and LenovoVantageService.exe.
• Code integrity violations were flagged for the Brave browser, which failed to meet Microsoft signing requirements for specific DLL files.
• A hardware-level error (Code 10) is reported for the Lenovo UEFI System Firmware.

Why it Matters

These symptoms suggest a potential rootkit or deep-level system infection that is actively subverting security software and core Windows services. Users encountering similar patterns of disabled security tools and persistent system crashes should prioritize backing up critical data and performing a clean installation of the operating system to ensure the integrity of the device.