It is certainly not a good idea for multiple users to log in to the same
copy of the database at the same time, because it can significantly increase
the chance of corruption. That is the reason that the very strong
recommendation for Access in a multiuser environment is for each user to
have his/her own copy of the front end (the user interface, with queries,
forms, reports, macros, and modules) linked to tables in the back end
(tables and data, on a shared volume). This is true whether the users are
running on their own machine or running on a server via Terminal Services or
MetaFrame. In the latter case, each user should have his/her own folder(s)
on the server, containing the separate copy of the front end.

I do not know if this is the cause of, or contributes to, the problem you
are experiencing with the secondary database startup forms closing. But it
is a factor that you should eliminate as a consideration, in any case. It
may be a good time to rethink the structure of your application.

There's an introductory presentation on Access in a Multiuser Environment
that I did for my user group that you can download from
http://appdevissues.tripod.com. It will identify topics that I thought
worthwhile to discuss, and a bit more. The best collection of detailed
information and links on the subject of Access in the multiuser environment
is at MVP Tony Toews' site, http://www.granite.ab.ca/accsmstr.htm.

 Larry Linson
 Microsoft Access MVP