"The project appears to be damaged, it cannot be opened"

Hi guys,

I'm in a bit of strife here. A project which I have been working on for the past month cannot be opened now as it "appears to be damaged" I am using Premiere Pro 5.5. I have no idea how to go about solving this, so help will obviously be appreciated. If it can't be opened, is there any way to save the bulk of my editing and open it in a new project?

Thanks a lot,

Josh