Sometimes when you reload a page, you get the same old crufty stuff even though you KNOW there’s an update.
Why is that? Well, when you load a page, your browser stores a local copy on your computer — this is called a cache. Whenever you visit a page, Firefox asks the remote server if there’s any update to the version that’s saved locally. If the host says yes, then Firefox fetches the updated page. If the last updated date is not after the date of the one you have locally, then Firefox displays the version from your cache instead, saving bandwidth and time.
Occasionally this screws up (usually because the host is returning bad info about when the page was updated). So if you just KNOW there’s an update, you need to reload the page, overriding the cache.
To do that, press Ctrl+Shift+R, or Ctrl+F5 — this is sometimes called a “forced reload.”