You could try clearing the cache and browser history. That can sometimes sort these things out. It's done in different ways in browsers but is usually in the settings somewhere. Without checking fully I think it's on the content tab in the cog then internet properties/options in Internet Explorer. A disk clean up in start, programs, accessories, system tools, disk clean up cans sort it out too. That is often really good as it clears all the temporary internet files too. I'm not really familiar with Firefox but it'll be in the settings that you clear it somewhere.