Changing Current User in Access 2000

We have a very large Access 2000 database running as a runtime that takes about 20-30 seconds to open on a 933mhz PC. We do not have the proper permissions to see what code is running at start-up. After the initial start-up, the database runs quickly.

To avoid delays for users, we would like users to be able to login and out without closing the database and opening backup.

Does anybody know a way to do this?