IE7 acting wonky with tab indexing

I've got a form which is attached to three other screens which are displayed horizontally. When I set the tabindexing and navigate through the document with tabs, everytime it reaches a "selectbox" it scrolls the page over so the le开发者_运维技巧ft side of the selectbox is in line with the left side of the page. Further tabbing moves the page back to it's original position.

Any ideas?