Workbench implements a project locking mechanism in order to help prevent the project from being loaded into more than one session at a time. When the project is opened, a .lock file is created in the project files directory. The project is unlocked by deleting the .lock file.
An improperly unlocked project can occur in situations such as program crash where the .lock file is not deleted, or if the project files directory is duplicated and the .lock file is copied with it.
If you open a locked project, you are asked how to proceed:
If the file is locked because of an abnormal termination, such as a program crash, click .
If the file is locked because the project is already open in another Workbench session, click .
Opening the same project in multiple sessions can result in corrupted project files.