Thank you, Petros, for your prompt reply.
I did try to open all available (5) auto-saves but they all exhibited the same problem. I have no problem with other projects. I can open old ones, current ones, new ones with the same settings. It is only this particular project with all its auto-saves that won;t open.
I also tried creating a new project and importing the problematic one… same thing. I tried using XML Wrench on the advise of a member of an Adobe forum. It didn’t detect any problems.
I believe, from the limited information the error window afforded, that a keyframe has gone astray, but I can’t pinpoint it or indeed get to it at all in order to eliminate it.
Please don’t give up on me.
Best regards,
Vasco