microsoft access 2007 / runtime

I have access application that I have given to two users.  They both have read access to the drive the application is loaded on. One user has access 2007 loaded and one user has the access 2007  runtime on their machines.  The user that has the full product can use the application with no problem.  The that uses the runtime version errors out after opening the first form.  Each form has a automatic save button after the users leaves the form.  when the user with the runtime tries to leave the form the screen goes blank.  I just want certain users to have read only access to the application.  So I only gave them read/execute on the drive the application resides on.