Have you tried to open your backup file? Have you save it in increments in smaller portions just in case the worst happens, you have something to revert to?

At the end of the day on what I can't afford to loose, I save to another drive which in turn makes a back up copy of its own and again to my desktop.

I've been burned once, haven't let that happen again. It was because I was trying to do a book, heavy with large pictures, and just was asking more of DRAW than it could do, I ended up doing the project in Pagemaker because the book was 85 pages.