Have you tried explicitly setting the height of the left column to be the same height as the rite column? I think that the rite column is taller than the left and this might be causing the problem that you see.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.