Previously unlocked tab locks after data is entered??

[climberboy2000]

I have a spreadsheet where I lock down the first couple rows and allow users to enter data in the rows below. Often times the lower section will become locked and I will unlock it so the user is able to enter their data. But when they save it and go back to the file later the lower section is locked again and will not allow them to enter any data. Why would it lock again after the fact? This file is used by many people and only happens to certain groups every month. Any ideas?