Thanks for your quick response.  Both the computer the form was originated/enabled on and the user's computer have the exact same date and time.  Our computers are synchronized using a central server.  Any other suggestions?

I am having the same issue as Tony.  I have enabled the usage rights using Adobe Acrobat Professional.  The users are able to fill out the form and save a copy.  However, after a few times of adding/editing data and saving the following message appears and does not allow the user to continue editing...