When you design a website, you specify a resolution. Most websites used to be designed for lower resolutions but as time goes by and most people have newer gear, the resolution gets upped. Most websites are designed in 800x600 to cater for the world-wide masses' monitor resolution but some are designed for optimum viewing on 1024x768. If your monitor resolution is 800x600 you will see scroll bars whenever you visit such a site.
If you set your screen resolution to 1024x768 you should be able to view all sites ok and you should not need to alter it back - once its done its done.
Or go out and buy a widescreen monitor like mine !!!!
Hope this makes sense !?