Startup error: stop code Critical Process Died

Hello, I am having some trouble fixing my parents' PC. They reported that it wouldn't start up correctly. The motherboard is an Asus P5K SE and the cpu is an Intel Wolfdale E8400 and has been running Windows 10 since last early 2015 (was running windows 7 before that, took the free upgrade).

When I got to it, I attempted to start the PC normally. The PC did not load Windows 10, went to a page about collecting information and reported the stop code Critical Process Died. The PC rebooted automatically, attempted an automatic repair but that failed. I tried to Reset the PC using the message on-screen, whilst keeping files, but Windows 10 said it was unable to do that. I tried advanced options, including boot in safe mode, boot in safe mode with networking, startup repair - all of which simply got me back to that screen.

System Restore is unavailable, which I find troubling. I went into the Command Prompt, expecting to find c:\windows\system32 - but instead it says x:\windows\system32. It's as if it can't locate the c drive. I rebooted again and this time went in to BIOS to check the boot configuration. The correct hard drive is selected as the boot drive. The drive in question is a NAS-quality Seagate 4TB drive (ST4000VN000), purchased August 2015 - it should be well below it's MTBF.

I rebooted again and got back to the advanced system repair options page. I tried again in command prompt, again in x:\windows\system32 and tried to run sfc /scannow. It finished the verification phase but could not continue. Back to square one.

At this point, I don't really know what to do. Any help would be appreciated. Is it possible that a windows update broke compatibility with this old cpu?

Caledon Ken said:

Have you try booting from and ISO or USB Flash drive?

Does this box actual have more than one storage device be it SSD or HDD. If so then you might want to run chkdsk on C: and it should see C: if you boot from Media. In the early days Microsoft shut off system restore by default and you had to go in and make sure it is / was enabled.

Once you get data off it may be quicker and less effort to do clean install. First lets boot off media and see if chkdsk will run. YOu can run to scan or scan and attempt to fix.

I've got an installation DVD for Windows 10, I can boot from that. I still can't use the Reset PC option - it goes through the motions of gathering the required information but then says it can't complete. I could try installing Windows 10, but I'd need to go Custom rather than Upgrade, and I'd prefer to keep the files if possible.

How can I run chkdsk on C: drive?

EDIT: I figured out how to run chkdsk on c: drive. Weirdly, command prompt says that the label for that volume is System Reserved. It's as though the partition with the actual Windows partition is gone.