Your browser tends to hold onto information (cache), and over time can cause problems. It is a good idea to clear out the cache on a regular basis.
The quickest way to clear out the cache is to hold down the CTRL + SHIFT + DEL buttons on your keyboard to bring up the Clear Browsing Data window.
The example below is in Google Chrome, but this keyboard shortcut works in any browser. Make sure the Time Range is set to All Time and that you have browsing history, cookies, cached images, and files selected. Then, click Clear data.