I have Windows 7 on my computer, which was newly purchased in March. Thunderbird email worked fine until May. At that time, messages from trusted persons began being delivered to my Spam Quarantine Summary instead of the inbox; even though I received messages from these people previously. The action buttons in the Quarantine Summary (deliver, delete, view, whitelist) do not work. Whenever I try one of these actions I get the message, "This page cannot be displayed." The links at the bottom of the Quarantine page (delete all displayed messages, manage your allowed/block list, etc. ) give me the same message. What can I do?