It looks like parts of the theme are missing, which could happen if Opus is run under compatibility mode, perhaps. (Details of how to check are here.) It may also indicate something wrong with the Windows install, or that there's something installed which modifies the way themes work (e.g. WindowBlinds).
If you switch to the full "Windows 7" theme (with Aero/transparency etc.) do things look correct? What if you then switch back to "Windows 7 Basic"? Or what about "Windows Classic"?
What does Explorer's location field look like?