… Does the sidebar move on the theme’s demo website (if there was a demo website) or in the screenshots of the working theme?
Try this:
– Go into your style.css page and find where it says #header and change it so that it floats right and see what it does.
You currently have your sidebar to float left, you know, and the fact that the sidebar is to your RIGHT tells me that glitchy and/or override coding allows the sidebar to show up on the right hand side in the first place when it should – according to the code – be floatin’ itself to the left.
Change that and see what happens.