Blue screen error for a second then continuous restarting

My laptop has a BSOD error which i've read about all day on various fora, but haven't been able to solve through the answers others has gotten.

After showing the Windows flag when starting up, there comes a blue screen for a split second and then the computer reboots. It does this continuously.

-I tried testing the RAMs by running a memtest86 test which ran through test #1 to #11 for 2 hours without finding any errors, i didn't know wether or not it would shut down by itself, so i eventually turned it off.

-I tried making a Windows 7 bootdrive on an USB-port so i could access "Repair my computer" and get into the command prompt through safe mode, but the screen only goes as far as the background image for the login screen, without showing the CMD or the user pic etc. So i'm not able to mess around with "CHKDSK" as i've read others have had succes with.

How do i fix this? Would it be possible to get further into the reboot process by running ubuntu on a stick and then mess around in the command prompt through there? Or would that be a waste of my time?

Thx beforehand
Michael :)