AB PLC5 program become protected

Can somebody help me figure out why our plc5 program suddenly become protected? We are currently commissioning a refurbished machine with ab plc 5/40e plc. Yesterday I can edit the program with no problem but this morning when I go online to continue editing the program, it was already protected. I might accidentally trigger the program protection bit but can't figure out where is that bit. I can edit the program offline without any problem. I am using RSLogix 5 sofware.

Thanks in advance.

Edwin

Project Tree look under Passwords and Privileges. See picture below.

And each program file properties.