login problems

Everything works fine for a long time until now. I can login user "b",which is newly created by root in safe mode(because I can't login my original account "a" all of a sudden).And everything works fine in the new account, but not in my "a",which appears to be stuck at spinning and no longer...

Since a week or so, I can't type my password to login at ML. I make use of a bluetooth keyboard and a magic mouse. They are detected but nothing happens when trying to type. Weird thing is that I also have a USB keyboard hooked up in order to choose my OS to startup with and the USB...