Selecting Manage Project - Unlock from the Session or Job Queue tab main menu or File - Manage Project - Unlock from the project editor menu unlocks the project and allows you to write to or save the project.
Normally, the project is locked because the analysis engine, em, is running an analysis on the project. You must stop the analysis before you can write to the project. You may stop the analysis by selecting Run - Stop from the Job Queue tab.
If you determine that em is not presently running, but the project is still locked, you may unlock it by selecting this command.
Warning: It is important that you conclusively determine that em is not running before you unlock the project. If you perform an unlock while em is running, you may corrupt your analysis results.