Can authenticate but not login in with my password !?

Can authenticate but not login in with my password !?

Here is my story :
there were days when I had my password and everything was fine.
I removed my password :
Opened User accounts
Unlocked it by pressing "Unlock" button
Selected my username (btw, I have only one user which is Administrator user)
Chose "Login without password"
Pressed "Change" button
and some day there came a trouble
i needed to authenticate (as I had no password I could not authenticate)
using Startup Disk Creator wrote Ubuntu 12.04 to a USB.
I "tried Ubuntu"
mounted my Ubuntu's filesystem (not Try Ubuntu's)
in terminal run gksu nautilus (No authentication was necessary)
opened etc/shadow file, and removed some_encrypted_text from this line :
wicked6:some_encrypted_text:15864:0:99999:7:::
Rebooted and opened my Ubuntu
in terminal run passwd myusername and changed my password
I got the message passwd: password updated successfully
I can use this password for authentication but not for logging in by pressing login button (I can log in directly on first log in {Remember that I had used login without password}. But when I lock my screen I need to press switch user and then press login, because when I enter my password it does not accept it)
Please don't advice me to reinstall Ubuntu, because I don't want. Help me to login in on Lock Screen. Thanks in advance.
P.S. I am using Ubuntu 12.04 :-)