It happened just after I updated to the latest version 16.4.1.
The workspace settings as: save; restore and keep undo information.
It was changed to none, and reset “customize start window” as default. It still re-opened when it was closed.
I am not sure exactly what the issue is. Can you please send me a screenshot or screencast to tech @ emurasoft.com ?
Please also export your Registry at HKEY_CURRENT_USER\SOFTWARE\EmSoft\EmEditor v3\ and compress to .zip file, and send it with your screenshot.