Thunderbird locked up

1 - I started using Thunderbird - I had over 100,000 emails accumulated in Yahoo. It is my understanding that if I move emails from the inbox to a local folder that after processing they will be deleted from the server. It is a long show many day process. But even after moving many they don't seem to disappear if I look at the online yahoo website after a number of sessions of doing this.

2 - Now when I bring up Thunderbird, there is a strange bar through the email display. If I click on anything the strange bar just wiggles. It looks like a dialog box not fully formed. I cant answer what question that it asks so i am just locked up. I have uninstalled Thunderbird, did system maintenance, and reinstalled it. It changes nothing.