Many site issues can be caused by corrupt cookies or cache. In order to try to fix these problems, the first step is to clear both cookies and the cache.
Note: This will temporarily log you out of all sites you're logged in to.
To clear cache and cookies do the following:
Go to Firefox > History > Clear recent history or (if no Firefox button is shown) go to Tools > Clear recent history.
Under "Time range to clear", select "Everything".
Now, click the arrow next to Details to toggle the Details list active.
From the details list, check Cache and Cookies and uncheck everything else.
Try the Firefox Safe Mode to see how it works there. The Safe Mode is a troubleshooting mode, which disables most add-ons.
(If you're not using it, switch to the Default theme.)
You can open the Firefox 4.0+ Safe Mode by holding the Shift key when you use the Firefox desktop or Start menu shortcut.
Or use the Help menu item and click on the Restart with Add-ons Disabled... menu item while Firefox is running.
Don't select anything right now, just use "'Start in Safe Mode"To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before using the Firefox shortcut (without the Shift key) to open it again.If it is good in the Firefox Safe Mode, your problem is probably caused by an extension, and you need to figure out which one.