Where is this project located?
Was it created by your current version of the program on your current operating system?
Are you sure you trying to open the .prel file using File/Open?
What kind of camcorder did the video come from that you used to create this project?
The project is located on D:/ harddisk.
Yes it was created by current version of Prem Elements 10 on current operating system.
Yes I am trying to open the .prel file using File/Open. Have also tried to open project file from Project file where I saved it.
Am using footage from a Canon Legria HFS200.
Have now deleted project, am starting a new one, editing and closing project, testing it will open again. So far so good.
Another idea... at the end of each day to a "file save as" for your project... and save a new project file with an incremental number so you may always go back one version of needed (KidParty01, KidParty02 and so on)
Thanks for your answer, I will try that.