Windows in a restart loop

[lmmc]

I didn't know where to post my problem. It's not exactly a BSOD problem.
So, I have this notebook Sony Vaio NW250AF since 2010. It never had any problem before. Four months ago, I installed Ubuntu with wubi (windows ubuntu installer) and everything went well, until couple weeks ago. Suddenly, my Windows began to restart every time it gets to the initial screen, the one with de Windows' logo. I believe that before this happen, there were an update on Windows, but I don't know if this is the problem.
The wierd part is that I can boot the Ubuntu, it actually starts and that's where I am now. However, I've never accessed any Windows' file from here, because some people say it can cause me problems.
I've tried everything I could find on the internet. Everything people do when there is this kind of loop on Windows. I also tried everything that people suggest when the safe mode gets stuck on classpnp.sys. I've tried bootrec and scan, but since I don't have the disc repair and I'm forced to use the repair on the notebook, I keep getting an error message telling me there is a repair going on. I've disabled the option of "restart whenever gets system error" and it just freezes in a black screen.

Things I've tried in a hardware level. I've removed my memory, i've cleaned everything.

Specs
- Windows 7 Home Premium x64
- Original OS
- OEM
- Age of system: 2 years
- Age of OS: 2 years. I've never re-installed.

 

[usasma]

Start with these free, bootable hardware diagnostics: Initial Hardware Diagnostics
Post back with the results and we'll move on from there.

 

[lmmc]

I ran memory diag and it passed without any error. I couldn't run hard drive diag because I have no idea of the manufacturer.

 

[usasma]

Use the Seagate Seatools test then.

 

[lmmc]

So, I got PASSED on both tests. :/

 

[usasma]

Based on what you've described you're going to have to try and reinstall Windows on your laptop. If you don't have the recovery disks you can get them from Sony. Here's instructions on how to do it (only for the USA, your country may be different): Order Recovery Discs (USA)

If you haven't backed your stuff up, you may want to do that before reinstalling Windows - as the reinstallation may delete all of your files. You can probably do that from Ubuntu - but I'm not at all familiar with how Linux works.