I am glad you got it working.
Would you mind sharing with us what you did?
I really don't know, but that is the purpose of Session Lock feature, to lock out the application until a valid user gets access to it again.
For that you will have to create your own Login form, which is very easy to do (see documentation) and add that functionality. Keep in mind that Session Lock will leave forms in their current state (ex: unsaved data, etc.) so you may also check for those things before closing any open form. There has been a couple of discussion about this in the forum, so search for the "Session Lock".