Windows Upgrade Help and more

Same here. I had the same problem. Running SFC didn't work for me, but a quick Windows Update fixed it. Hope that helps.

Can confirm. You could also try a clean install of Windows 11 instead of the upgrade, as that often resolves leftover performance issues. Another option is to check if your specific Dell model has updated drivers or BIOS available on their support site.

Agreed, that's a good call. Also, make sure your BIOS is up to date, as an outdated version can cause exactly this kind of boot loop.