Poor stroke quality.

Hello there,

My problem is simply this:

Look at the corners. Looks bad.

My settings are these:

I'd like to know how to make that stroke look smooth on the corner. It used to work better in CS5.

Thanks in advance.

Edit: I'd also like to say that smart guides don't work for me. They used to appear when I move my mouse over any object. My smart guides are on as showed in the reference images above.