PDO Printing Problem

My collection of model files is on a set of thumb drives, so no models were lost when the hard drive crashed. But now there's a printing problem with the new hard drive and PDO files. The models seem fine in the Pepakura viewer, but half come out of the printer looking like they've been cut into misaligned strips. This problem is only with PDO files, and not even all of them. Can anybody explain why -- and how to correct this problem?