I've recieved the dreaded "General Error" message myself. I couldn't get the project open by just clicking on it. I was lucky to know someone who knows how to do a tracer through the terminal window to find the problem. The problem turned out to be missing files that FCP was looking for. Once he opened the project we had to either find those files and recoonnect, replace them, or delete the files in the browser so that FCP would not look for them.
On top of that I copied the project and renamed it. After all that, the original project file could not be opened. So, I had to work off the Copied project file.
Best of luck,
G-