Definitely don't do what I did...
I just had this error myself. I discovered, as a user recently pointed out, that the Fostex does indeed save every take you do on the track as an "event" - every botched solo or vocal take, every anything. So I connected my laptop to the machine and went through and deleted some of those "events" that I knew to be ones I was not keeping. I am utterly defeated-feeling now. Even though the tracks I deleted were recorded over by me, when I took them off the Fostex disk it completely screwed up the entire song. The volume on some of the tracks is totally, insanely overly loud. There seems to be no way of fixing it. It doesn't even really want to load up the song anymore. So if anyone has any ideas how that might be fixable, that'd be great, but otherwise, just make sure you don't do that.