The problem your having is not related to entering in your password.
Windows is restarting the computer because the OS is crashing and automatically restarting.
What you have to do is disable that options so you can see the error and Google it on another PC to find a solution for it.
Turn on your PC and start hitting the F8 key until you see Advanced Boot Options at the top of the screen.
Use the arrow keys to select the option that says "Disable automatic restart on system failure".
The computer will continue to boot up but now will not automatically restart when a critical system error occurs.
Your going to see something like this:
You need to right the 2 lines I circled and search it to see what the problem might be.