You may be using any content which width is larger than the content area. Most probably for using any plugins. Please check your plugins activating and deactivating. We wish we will investigate line by line of our users site code. But unfortunately we have to manage a large user base. The Practical situation is difficult. When you will face any problem we do recommend to overwrite the theme files. If the problem exists that problem is due to any plugins. You should also check your html input within any page/post editor so that no missing closing tag is present.
