Marco trouble with any window manager at start

Hi,
Running Ubuntu Mate 18.04. Most times I login, the window manager, run by Marco, does not work. Symptoms: cursor turns to a cross, windows have no title bars and cannot be moved or shut, some times a message about window manager, nothing on the desktop, icons, shortcuts, etc. do not appear. I use a shortcut in my bottom menu bar to "Mate Tweak" and change the window manager to any other on the list and things work for the rest of the session, except items on desktop that do not re-appear. This happened last year, and I followed a suggestion that worked, but it came back and can't find that suggestion. Is it possible to re-install Marco or change to another manager without loosing all ?
Thanks

Christian (xian)

Did you try reinstalling with sudo apt reinstall marco?