Why do I have so many Tentative scripts in my History?

As the administrator of the project do the following:

• View the History tab
• Find the oldest script that is sent by you (the admin) and is still tentative
• Double-click on that script and look at the "Awaiting acknowledgments from" box. It will show one or more users who are not responding. They have probably left the project long time ago. Write down their user IDs
• Open Project>Members dialog box, find the users with the IDs from the preceding step
• If you know that they are no longer members of the project, remove them from project. If you're not sure, change them to observers.

After one more check-in and the acceptance of the script, the history should clear up. If not, repeat the above procedure again.