We need more information. Tell us about your troubleshooting procedure:
1. which process triggers the error? Opening? Saving? Viewing? Rendering?
2. At what point in the process does the error occur?
3. Have you changed anything that allowed you to continue successfully?
– moved footage files to another drive?
– imported the project into a new project?
– disabled any effects that may be causing the error at the point where it is noticed?
– opened a previously saved project?
If the error occurs when opening the project, try importing it into a new project, or opening with caps lock on. If that fails, and nobody here has the answer, you should call Adobe and pay for a tech support incident. Sometimes they can dive into the file and fix it … sometimes they can’t.
Next time, you’ll save the AEP under a new name hourly, yes?
Steve