Expression (1)-line consoles have a double density (DD) disk drive. Many sites have been using high density (HD) disks with these consoles because either they don't know, or they can't find any dual density disks. Using high density disks in these consoles is very risky, as the disk drive writes a DD format on the HD disk. Using HD disks in a DD drive can damage the write head of the drive as well.
If you save a show file onto a HD diskette and try to read the diskette on a PC, the PC will not be able to read it. The PC drive will see the high density "hole", or punch out, and look for a high density format. This HD "hole" is the open square on the opposite side from the write-protect switch. This hole is used by disk drives to sense the presence of a high density disk.
ETC's recommendation is to use only DD diskettes in Expression, Impression, Concept, Microvision, Microvision FX, and other "1-line" consoles. Results will vary if you use HD diskettes.
To rescue a showfile from a DD-formatted HD diskette, you can try putting tape over the HD hole on a HD diskette, which may help somewhat, depending on the diskette drive. This same trick may help with reading DD-formatted HD diskettes in a PC, so that you can read the diskette contents to save onto a true DD diskette.
You can also try to run SCANDISK on the taped-over floppy if you are unable to read the contents. This may allow you to save contents to a true DD diskette.
Please remind anyone having disk problems to record their show on at least 2 disks (if not more).