Same thing just happened to me. Any luck resolving your issue? Any tips?
Jack, what's the "cos file" you mentioned in your reply?
I had recently posted a question on how to avoid this, but it happened anyway.
I moved all of my image files to a new, larger hard drive, and now Capture One 5 Pro cannot find any of my sessions, and all of my adjustments have disappeared. I have tried opening a session by selecting the col.50 folder, but each time I try this, the program quits.
Surely, C1 can manage to find files on a new HD. What is the secret?