I'm having trouble setting up a new workgroup information file for an existing Access database (Access 2000) it's driving me crazy... can someone please help??:

-I had the database working fine with multiple users and a workgroup information file.
-The information file got corrupted (or something) and didn't work anymore, so I followed the help and created a new workgroup file with all the same IDs.
-I joined this new workgroup and I can get into the database fine but it always logs me in as "Admin" and doesn't prompt for a username when I open Access like it used to.
-Access help says how to deactivate the prompt but doesn't say how to activate it again, which is what I need to do.