Comment 4 for bug 481682

Thank you for the update. You seem to have Flash installed. You might want to try removing swfdec-mozilla as there's no need to have 2 flash players installed as they somtimes conflict. If that doesn't work, please try the following suggestion and let us know what happens.

Sometimes Firefox profiles can become corrupt and/or extensions can conflict. Could you please try this with a new profile and see if the problem still exists? You do not need to delete your old profile to test. If this helps, you might want to try to disable all your extensions and re-enable them one by one until you find the problematic one.

You can start the profile manager with the following command:
firefox -ProfileManager