Thunderbird 3.12 issues:
(1) The "display next message" command (N key) fails, either requiring confirmation, or trying to display next Spam folder message instead of current Inbox message folder item, or is unresponsive.
(2) In a message window, the Delete button frequently errs when clicked, deleting the current message (wanted action) but also deleting the next, unopened message (unwanted action).
EMPLOYEE0Larry, thank you for reporting the problems you see.
1. Do you see these behaviors with Thunderbird started in safe mode?
2. Is the folder pane (left side) in Unified Folders or All Folders?
3. regarding problem (2), do you also see this behavior if you right+click the message and choose delete from the context menu?