Thunderbird V38.5.1 on Imac OS V10.7.5. This problem started 2 days ago. I cannot open my emails on my Imac. I can get my emails on Yahoo via Firefox and on my ipad and iphone. I can also get my emails from my other Imac computers. My problem is only on my personal Imac computer. My emails show up on the Thunderbird screen but when I click on any email on the screen, the colored processing wheel starts spinning. My computer says that Thunderbird is not responding and advises me to force quit the application. When I force quit and reopen the Thunderbird application, the problem continues to exist. I cannot send any emails. I can receive the emails as I can see them on the Thunderbird screen but, I cannot open the messages due the fact that the colored processing wheels starts spinning whenever I try to click a message or any heading or anything located in the menu bar.