Firefox 10 for Windows and Mac OS X
- From the Tools menu, select Clear Recent History.
- From the drop-down menu, choose Everything and make sure Cache is checked.
- Click Clear Now.
Firefox 3.x
- From the Tools menu, select Clear Recent History.
- Select the Time Range to clear from the drop-down menu (Everything is recommended).
- Click Details to choose what history elements to clear.
- Select only the check box for Cache.
- Click Clear Now.
- Exit and re-launch the browser.
FireFox 1.x-3.0
- From the Tools menu, click Clear Private Data (or Ctrl+Shift+Del).
- Make sure the box is checked next to each option for which you wish to clear private data (browsing history, cache, cookies, authenticated sessions).
- Click Clear Private Data Now.
If you continue to have trouble successfully clearing the browser's cache, repeat the steps above and restart your computer.