If you haven't used Firefox in a long time and it's behaving oddly, you might want to try resetting it to defaults by picking "Troubleshooting Information" from the Help menu, then clicking the "Reset Firefox..." button.

As somebody who occasionally has a flaky internet connection, I'll agree that pump.io's AJAX-heavy interface is often frustrating (say, when you click a link, and the request times out, and you're stuck watching a spinner for eternity) but it's gotten a lot better since the initial migration and a shift-reload generally clears things up.

(entertainingly, I had such a freeze during my first attempt to post this comment, and had to reload the page to make it work)