Epson 486SX - Manual (Page 173)

7. You may have entered an incorrect diskette drive type when
you ran the Setup program. Run the Setup program again
to check the setting. See Chapter 2 for instructions.
8. Did you receive one of the following MS-DOS error
messages?
Disk Drive Error: Abort, Ignore,
Retry?
Disk error reading drive d:
Disk error writing drive d:
If you see one of these messages, make sure the diskette is
properly inserted in the drive and then try the operation
again. If the problem persists, try removing the diskette and
reinserting it.
If the error message still occurs, you may have a defective
diskette. Use the COPY command to copy the files from the
bad diskette to a new diskette.
9. If you see no error messages but there is something wrong
with the data in a file, the operating system or an
application program may have updated the storage
information on the diskette incorrectly. This is probably the
case if you have one of these problems:
Part of a file is missing
A file includes parts of other files
An expected output file is missing.
Use CHKDSK to make the necessary repairs; see your
MS-DOS manuals for instructions.
B-18 Troubleshooting