Unlabeled checkboxes on the page
I'm working on a forum theme and today I noticed something odd: there is a checkbox next to each comment, plus one in the User Menu. When I click on them, a popup message appears asking me to do something with the selected comments/discussions. These checkboxes have the CSS class "AdminCheck", but I couldn't figure out what they are for, why they aren't labeled and, most importantly, why there's one appearing on the top of the page. It's true that I'm modifying the theme, but I didn't create it in the first place (I took the TraditionalChocolate as a base) and I can't really figure out what's going on here.
Below you can find a screenshot that shows the issue. Thanks in advance for the help.