Problem is on one of 4 PCs; normal email page appears with focus error window… click on “OK” immediately CLOSES all EMClient windows; this PC happens to be home wifi laptop but changing to hardwired ethernet connection still has same problem… have reinstalled multiple times… 
To check if it is the database that is causing the problem, you can rename the database directory.
Close eM Client, and then rename C:\Users[username]\AppData\Roaming\eM Client. You may have to show hidden items in Explorer to do that. When you restart eM Client, it will be with an empty database. If that is not the problem, close eM Client, and then delete C:\Users[username]\AppData\Roaming\eM Client. You can then rename the previous one back to \eM Client.
Gary… Thanks very much… It worked just fine… I never suspected that it would be the database, and I actually had included that “Snip” by accident (GLAD I did !!)
Thank you again… Art…