Iain, the problem is simply put, yes, you cannot have a 960px wide page fitting into an 810px wide Placeholder without code to hide the x-scroll.
Either make the Placeholder as wide as songs pages' width
OR
Reduce the width of the songs pages.
For the jumping left, the page is simply moving to the position of the Anchor.
Change the Anchors to be on the upward arrows.
Seriously though, by the time you add the links and the music/video the filesize of the songs page you have will kill your website for a viewer: it will take a long time to download.
Split the songs across pages.
Acorn
Bookmarks