"This appears to be an issue with PC Exchange 2.1.1 and the way some systems format floppy disks. Floppy disks that have this problem have "FAT16 " written to their boot records; these disks are actually FAT12 directories. Apparently PC computers, PC Exchange 2.0.7, and earlier versions ignore this field on floppy disks. PC Exchange 2.1.1 checks this field, determines the floppy is FAT16, and reads data from incorrect clusters on the disk."
There are two work-arounds:
Use PC Exchange 2.0.5 or 2.0.7 on systems with PC Compatibility Cards.
Format DOS floppy disks on the Macintosh.