Suddenly my computer requires me to log in.

I didn't change any options that I know of and now I can't find out how to change it back.
I want my PC to boot up without me. I am the only user so I don't need those stupid account thingy. No clicking on names, no entering of passwords..... just boot up my PC.
Where do I change this? I have found the user accounts options, but no useful option so far.
Thanks!
And this time I won't answer myself because I'm going to sleep!
