Edit using internal SSDs or high-speed, properly configured network shares.
The absolute safest and most effective method to "unlock" a problematic EZP file is to bypass it entirely and restore a clean, functional copy from the automatic backup archives.
If the .ezp structure is completely broken, you cannot open it natively. However, if you have a secondary backup or an exported XML/AAF sequence from a previous rough cut, you can rebuild the project: Create a new project. Go to > Import > AAF/EDL/XML . Link the original source media clips back to the timeline. Re-linking Missing and Offline Media
The EDIUS .ezp file represents a "Walled Garden" approach to project management. "Unlocking" it in the sense of bypassing versioning is technically unfeasible due to structural dependencies. While forensic analysis of the binary data allows for potential data recovery or partial conversion, the format remains resistant to full open-source reverse engineering.
In the worst-case scenario, the .EZP file is structurally corrupted AND locked. You need to extract the timeline data.