Thank you for your post.
How long is it before a user is kicked off? The default time limit (no activity) is 15 minutes. I don't have FileMaker Pro 7 to test, but in FileMaker Pro 11, when you go into Sharing -> Instant Web Publishing..., go into Advanced Options and there is a setting "Siconnect inactive accounts" to change the number of minutes. If this is set to 5 minutes, then if the guest is inactive for 5 minutes, he/she will be kicked off.