How can I safely back up my files and reinstall Windows 11?

From Windows, you can try Settings > System > Recovery > Reset this PC. Choose the option that removes everything if you want a clean reinstall, but understand that this wipes the Windows drive. The safer approach is to make a full backup first, create Windows installation media on a USB flash drive, boot from it, and carefully select the correct internal drive during setup. Do not format or delete partitions until you are certain the backup is complete.

If you’re not sure what Hyper-V or virtualization means, don’t change BIOS or disk settings yet. First make at least one verified backup—ideally two copies in different places. An external SSD is useful, but it should not be the only copy of irreplaceable files. After reinstalling, restore your personal data manually instead of assuming the reset process will preserve it.

Before reinstalling, copy your important folders—Documents, Desktop, Downloads, Pictures, Videos, and any application-specific data—to the external SSD. Also check for files stored elsewhere, browser bookmarks, password-manager data, game saves, and any cloud-sync folders. Open several copied files from the SSD to confirm the backup actually works. A clean install will normally erase the Windows system drive, so you’ll need to copy the files back afterward. Use a separate USB flash drive to create the Windows installer rather than using the same drive as your only backup.

A HYPERVISOR_ERROR doesn’t automatically mean the CPU is defective, and reinstalling Windows may not fix a hardware problem. Faulty RAM, drivers, BIOS settings, virtualization software, or firmware can also cause it. Run a memory test from a bootable USB, update the laptop BIOS and drivers from Lenovo, and temporarily remove or disable nonessential virtualization software. Crash dump files can help identify the actual cause.