Have you consider saving data files in a different folder once they have been completed? Keep working data files in a folder that is only accessible by people who are entering the data. Once all the data has been entered and verified, then save the data files to a public folder that can be viewed by those who need to view it.

Also this prevents questions where only part of the data has been entered for the month.

Another idea is for user that only need to view the data is to use FN Report viewer. This product just runs all the reports. It does not allow acces to enter any data.