First of all, please, the best way to attach a picture is not... a photo. Use the grab command: just type in a browser the box IP address followed by /grab. For instance, if your box IP is 192.168.0.33
192.168.0.33/grab
and then save (right click) the picture you got.
This will also avoid to attach a rotated picture and the picture will be perfect, not just a more or less blurred photo.
Second: if this bar does not pertain to the skin, is surely some dirty plugin you installed. Which one, only you might know.