KSOD, Windows 7 (Solved!)

I would have not known about this issue that seems to affect quite a lot of the Windows 7 and Vista users, had I not encountered it myself the other days. If BSOD, the Blue Screen of Death is more widely known and causes are being addressed (more or less), the KSOD, or blacK Screen of Death is less encountered and causes I would say are still to be identified. Affected Operating Systems are, from what I've come across the internet, Windows 7 and Windows Vista.

There seem to be two manifestations of KSOD, I would call them BLP and ALP, the Before Logon Page and After Logon Page. These names come from the actual moment of getting a KSOD.
A) ALP takes place after you have passed the Logon Screen and implies you are actually able to logon to your account. The mainly spread symptom is that you logon to your account, yet right after that your screen goes blank and explorer.exe does not actually start, so you can not see your desktop. Now, logging on gives you access to Ctrl-Alt-Del and Task Manager, and the solution that seems to do the trick is to start or restart your explorer.exe. Or you could restart in safe mode with networking and start using the internet to find a solution. Because that is possible
B) On the other hand, BLP, the KSOD that I encountered, happens before the logon page, and the symptoms are: after the Windows splash screen, you get to the "Press Ctrl-Alt-Del to Logon" screen, but when you press that key combination, nothing happens. Oh, wait, you just get a blank screen, with a "live" cursor, which you can move around. And that's it. No Task Manager is available. Nothing is available except restarting your computer and getting to the same point. Restarting in Safe Mode doesn't get you anywhere, in fact no F8 option gets you beyond the Logon Screen (except the "Repair your computer" option - or whatever it is called - we'll talk about this a bit later).

Well, if your black screen of death appears before the logon page, i.e. you can not logon to your account, it's time to pay your computer geek friend a visit and start reading Google results. A lot of them, since the solution I encountered happened some 10 pages (of Google Search results) later. And since it took me about 6-8 hours, I really think I should share it with whoever stumbles across the KSOD.

As I have stated before, the cause is still not completely identified, so the things I'll present may or may not solve your particular problem. 
Of course, solutions that will work nevertheless, are to reinstall the operating system (and losing all your settings), or to format and then reinstall (in which case you also lose data). Before getting that extreme, here are some tips that might save your data:

0) Before everything: some of the actions below will require a command prompt. If you're having BLP KSOD, a good way to get to a command prompt is to press F8 during booting up and selecting Repair your Computer option. That will get you to another list of options, one of which is starting a command prompt. It should also be ok if you can hook your HDD in another computer (a tad difficult with notebook HDDs)

1) some people have had issues with the win event logs. You can try deleting or renaming the folder C:Windows\System32\Winevt\Logs. You should be able to get there using the command prompt.

2) Win 7 "Repair your Computer" action gets you to a list that includes something like "Start-up Repair". Try running that and see what you get. It didn't work for me.

3) Along with the Startup Repair option, you can also see the System Restore option. Try that one. It should work, if you have a recently created Restore Point. Not the case for me.

4) The one thing that actually did the trick in my case was a registry restoration. Here's the details:
- get to command prompt.
- navigate to c:\Windows\system32\config
- here you should see a file called SOFTWARE if you're using Win7, and also a software_previous file if you're using Vista. 
- if you don't see a software_previous file, check the path: C:\windows\system32\config\RegBack and see if there's a SOFTWARE file in there as well. If there is, then:
- the file in RegBack is your backup. Check the timestamp and decide if you're going to use this. 
- in my case the file was 8 days older than the "current" file, so I went ahead
- simply replace the SOFTWARE file in [..]\config with the one in [..]\config\regback

There is much more info on the internet about this, and all the cases of KSOD are quite dissimilar. My guess is that it happens after installing some new software, button-resetting your computer and somehow have Win 7 perform a lockdown on the registry set.
If the tips I provided don't solve this, keep looking on the internet - there's a lot of reading to do. Although, if you don't get to the bottom of it within 15 pages of Google Search results, or it's taking more than one-two days.... you should reinstall...

Where I found the solution that worked for me: Marc Gregoire's Blog

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