To clear the Firefox cache, bring up the Options menu, click on "Advanced," then click on "Network," and then in the "Cached Web Content" section click on the "Clear Now" button on the right.
To clear the Internet Explorer cache, bring up the Internet Options menu, on the "General" tab go down to "Browsing history" and click the "Delete..." button (don't worry because this won't actually delete anything yet), once the next page comes up be sure to uncheck the box next to anything you might not want to delete (like Passwords, History, Cookies, etc.) but make sure the "Temporary Internet files and website files" box is checked, and then click the "Delete" button on that page.
I'd have to look up how to clear the cache in other browsers like Google Chrome, Safari, etc. But I hope this helps.