My Finder file detail headers looks weird
You used View » Arrange By or a ctrl+&#x2318;+[number] shortcut. It's new in Lion. Remove it by selecting View » Arrange By » None (or pressing ctrl+&#x2318;+0).

Hold down &#x2325; while opening the View menu to get the older Sort By… menu, or press ctrl+&#x2325;+&#x2318;+[number] instead.