Garageband deleting saved data?

Hey all- I have had three instances (very frustrating, all of them) in the last year in which, after working hours on a garageband project, came back to find the project missing a lot fo what I had done. In two of the instances, when I returned, I found all the tracks I had added (piano, bass, etc) on the left, still with the automation I had put on the takes, but with the takes themselves completely gone! The third time, this morning, I revisited a project that I had worked on and saved (obsessively, since the second instance of losing data) last week- I had even closed, reopened, and relistened to this project several times since working on it. Today, after not touching it for four days, I reopened it to find that a lot of work done had disappeared- some sung harmonies were gone without a trace, not even leaving behind the automation or the empty track like the first two times. What the farts?!?!

This is driving me absolutely bonkers. Is anybody else experiencing this? I even went into my Time Machine backup to check out the last time I saved this project and tried to open it to see if the work was there, but it was gone from my time machine as well. >:( I'm getting real huffy and puffy over here and don't understand what is going on. Auto save is on, and I save a lot besides.

If anybody has similar problems with garageband or if anybody from the Apple center could shed some light on this I'd be chuffed. Thank you.