Another newbie

When I try to load DBUWIN, message says other users still in MOM, dbuwin cannot load. I know there's nobody using MOM, call the suspected user just to be sure, he says no, he's not in MOM, but when he tries to login it says ID already in use!

How do I force all users out? I need to get in dbuwin before users really do get into the program, so I do my work at nite - HELP!!