The daugther of one of my friends had a PC that would not start. Not that I like to mess with that - had done that too often - but helpful as I am I brought the PC home.
It failed with UNMOUNTABLE_BOOT_DEVICE STOP: 0x000000ED (0xaddress,0xC0000006,0x00000000,0x000000)
I searched the net. Found several articles but not really anything that seem 'correct'. Finally, I found an article on Experts-Exchange.com. Well, I could not get to the answers as I do not have an account, but sometime Google's caching feature are very useful...
So this is how I did it based on the answers I found -
Start the recovery console. If you do not have it installed - or when that version does not work - like in this case, boot from an installation CD and select R for repair. You can easily mix languages - I used an English CD on a Danish Windows
Run these command -
chkdsk c: /r /p
exit (to reboot)
That is it.