M17 wont boot windows, error 0cx000021a and BSOD

Hi,

My sons fairly new (mid 2013) Alienware M17, windows 8.1 suddenly stopped booting up.

it locks into a loop of displaying an error message and restarting itself.

I checked BIOS, and it shows up the correct 2 hard-disks (normal one and a solid state one).

When I use a command prompt to open notepad - in order to try save his key files before a refresh/re-install then only drive x (very small?) is listed - no C, no partition.

When I used BIOS to set it to boot from CD, it will go to the install or repair, but when I try to refresh it says the drive with windows is locked (is this referring to the CD?).

When I try re-install windows from the DVD (which came with the laptop) it tells me the computer booted from CD, I need to to remove the cd and reboot - which takes me back to square one, it cant boot.

He tells me now that he didnt create a respawn disk. To be able to fix it at all would be great, to be able to save a few files before any wipe would be perfect.

Just before the problem started, he did install a new game, from steam (not a pirate or torrent). 

Any help would be great :)