Grey screen after login - Blue Screen of death from CMD+R Mid-Late 2011 15inch Macbook Pro


7200RPM harddrive
user upgrades
- crucial ram 8GB right after initial purchase
- Corsair ram 16GB since August 2012 - http://www.amazon.com/gp/product/B0076W9Q5A


Running FileVault2

Came with Lion installed; Currently on Mavericks (Previously Mtn Lion)

Boot up

Login

Hear hard-drive crunching away

Spinner disappears, hard-drive not making noise

Grey screen, left it this way for over 30 minutes, no change


I have tried almost all of these: http://support.apple.com/kb/ht1533

Boot with CMD+R

No login needed

Blue screen of death


Boot with C

With Mavericks on USB


Goes to login first
Then same grey screen


Boot with D


Goes to login first
Then same grey screen


Boot with OPTION key


With Mavericks on USB
No login screen
Select USB





Wait
Then same grey screen


Boot with SHIFT


Goes to login first
Then safe boot progress bar





This takes a long time
Then the apple and spinner 
Then the "do-do-da" sound of a typical re-start
Then the login screen
Then same grey screen


Boot with CMD+V


terminal output along the lines of:



  bootfile path System/Library/CoreServices/boot.efi



goes by really fast
Goes to login first
Then lots of terminal output
I have pics but hard to read, could zoom and crop if needed, here is right before grey screen




NOTE: VBoxDrv - I think this might be VirtualBox which I definitely have installed? could be unrelated?

Boot with Option-Command-P-R


Reset NVRAM: http://support.apple.com/kb/HT1379
After reset auto reboots
Then login screen 
Then same grey screen




this is where it starts to get good: 

Boot with CMD+S


terminal output along the lines of:



  bootfile path System/Library/CoreServices/boot.efi



goes by really fast
Goes to login first
Then lots of terminal output


Now I have an interactive terminal !!!! Logged on as root

Followed some advice here - https://discussions.apple.com/message/22355542#22355542

rm /Library/Preferences/com.apple.loginwindow.plist
rm /Users/&lt;admin_acct&gt;/Library/Preferences/com.apple.loginwindow.plist


says 'Read-only file system', tried with sudo and same result
also tried chmod 777 on the files but same message

Any ideas what to do next, besides taking to Apple Store (or local apple tech in my case)?

can I go from CMD+S terminal to 


Apple Hardware Test
Recovery System
Disk Util


All of my data is backed up on Timemachine and I have been up and running on a different machine for now, so a clean install would be great - thinking this could be a hardware issue though?

UPDATE 1: 

From "Single User Mode" CMD+S

Executed: /sbin/fsck -fy which had the following output


Ran it multiple times; it only found issues during the first run, but still no luck - grey screen after login, then ran 

/sbin/fsck -fy
/sbin/mount -uw /


This allowed me to do writes so then I removed both com.apple.loginwindow.plist files (see above), no change; still hangs when trying to login

UPDATE 2: [SOLVED]

Thanks to @smr 

see also: Boot hangs on grey screen (even when booting from USB drive with fresh OS X install)

Boot into Single-User mode

# Execute the following commands:
/sbin/fsck -fy /
/sbin/mount -uw /
mkdir /Disabled_System_Library_Extensions
cd /Disabled_System_Library_Extensions
mv /System/Library/Extensions/ATI* .
mv /System/Library/Extensions/AMD* .
touch /System/Library/Extensions
exit


NOTE: this leave the computer with suspect graphics, going to do a re-install; apparently a GPU failure: http://www.macrumors.com/2014/01/17/2011-macbook-pro-gpu-glitches/
Though I didn't experience the blue screen, this does sound a lot like the issue that I described in Boot hangs on grey screen (even when booting from USB drive with fresh OS X install) (I posted as a different user since I didn't immediately have my StackExchange credentials handy).

It seems there are an increasing number of people experiencing failure to boot due to the GPU having died. I'm in Australia and we have just (and are still in) a bit of a heat wave which may have exacerbated the problem.

Anyway, it may be worth trying the steps I outlined in the Q&amp;A I referenced above, particularly booting into Single-User mode and moving the ATI and AMD related extensions out of the way.

HIH