OS X Login Issues

I'm having the strangest problem with my Cube, and I figured you guys could probably help me. Here we go.

I shut down my Cube every night, as it's in my bedroom and the fan from teh Radeon is annoying when I'm trying to sleep. For the past couple of mornings I've had a really weird login issue when I start back up.

I boot just fine, all the way through to the login screen. When I enter my password to login the system doesn't accept it the first time around. It does that screen shaking thing to tell me that I've entered the wrong password. I enter the password a second time and the system lets me login smooth as silk. At first I thought I was entering the password incorrectly, but I made sure to type it slowly while looking at the keyboard this morning. Same routine: shake, re-enter, login. I just tried it again to see what would happen, and it's still giving me sh*t! What is the problem, and what can I do to fix it?

I know that I could just uncheck "login at startup", but I need to use password protection to keep my retarded Mac hating roommate from doing any damage. Suffice it to say that disabling password protection is not an option. Any thoughts as to what I could do to fix this? Thanks!

 

Yo Alex, the old password was 8 characters. I reset it and it worked like a charm. Thanks buddy!