Windows boots but won't load (Black screen with cursor)

[Sorry for the long post, but I feel the need to fully explain my situation]

I have the following problem:

I turn on my PC, and Windows shows it's normal loading screen, after which it goes into a completely black screen, with just the mouse in the middle. By the cursor size I can tell that it's in a low resolution, probably 800x600 (compared to my usual 1920x1080). I am able to move the mouse around, but with no particular use without something to click on. No other keyboard input seems to work, except for Shift key 5 times, which brings up the Sticky Keys dialog box (with just "Yes" or "No" options, no other link); and Windows key+U which brings up the Ease of Access center. Ctr+Alt+Del does NOT work.

So far this is what I have tried (in chronological order):

1. Boot into Safe Mode, Safe Mode with Networking, Safe Mode with Command Prompt, Booting in low resolution video, Last known good configuration: all yield the same result as booting normally.
2. Repair your computer:
   
   1. Startup Repair: Found Registry Errors (I realized and fixed this later on)
   2. System Restore: Did not find any previous restore points (I know for sure that there are, I made a habit of making restore points regularly).
   3. Windows Memory Diagnostics: Did not find errors.
   4. Command prompt:
      
      1. Ran chkdsk /f /r command, did not report errors.
      2. Ran sfc /scannow : I don't remember the exact report, but it asked for a restart to finish repairing problems. I restarted, and ran the command again for the same result.
      3. Forced the scan with: sfc /scannow /offbootdir=c:\ /offwindir=c:\windows , it found and repaired some errors, still could not load windows.
3. Ran Dell Startup Diagnostics, found no errors.
4. Ran Startup Repair again, found the registry errors again. I found the solution to this in a Microsoft Help forum ( answers.microsoft.com/.../f77d5355-b8be-41d6-af24-cae994e1768f ), and fixed the issue. I rebooted, but the problem persists.
5. Startup Repair now finds no errors. I tried System Restore again, it found 2 restore points dated AFTER my problem started. I decided to restore anyways, but neither of them worked.
6. I ran Windows Defender Offline:
   1. Quick Scan: and found 2 threats and removed them.
   2. Full System Scan: found 4 more threats, removed 2 of them, the other two couldn't be removed because they were within an ISO file.
7. I tried Steps 1, 2 and 3 again with no luck.

With each step I am aware that I'm closer to having to reinstall Windows, so I decided to see if I could still access my HHDD to save my personal files. I made a Linux live CD (with Ubuntu), but I am having trouble mounting the drives, because they are in a RAID0 configuration. "sudo dmraid -s" gives the following error: "ERROR: isw: wrong number of devices in RAID set "isw_dbdffjficc_ARRAY0" [1/2] on /dev/sdb".

Important Details:

I changed my graphics card about 4 months ago (an Nvidia GTX 750ti for an ATI Radeon HD 6450), and I was told that I may be running short with the Power Supply. The new card asks for a minimum of 450W and I think my PSU is 460W. This may or may not have something to do with this issue, I have no idea.

The RAID0 configuration of my 2 500GB Hard Drives brought me a lot of problems from day 1. One of the HDD would randomly fail (I am able to hear a different clicking sound when this happens), and the computer would crash. Upon startup, it would ask for a boot device. The Dell startup utility would then only recognize 1 of the drives, but would finish without errors. After a restart or two, all would be fine and windows would boot normally (aside from the usual error recovery screen) without any sign of corrupted data or anything. Like I said, this has been happening form the day my PC arrived, but restarting a couple of times always fixed it. As of now, both HHDD seem to be working fine, the Dell utility recognizes both of them, and does not find errors in any of them, and I can access any directory from the command prompt.

Is there anything else I should try before reinstalling Windows?

Before the install, I would really like to be able to recover my files (I have important documents from college), is there any way to do this?

Sorry again for the extremely long post (and for any language errors, English is not my native language), and thanks in advance.