It sounds like 1-2-3 doesn't like the size of your file.
>>> *Check to be sure you are not opening a 0 file.
This probably refers to a zero byte file. You can check the file size in explorer.
>>> *If necessary have the file transmitted again using a communications protocol that does not change the size.
This suggestion is for the cases where you may have downloaded the file from another source (and the file may be incomplete as a result). It sounds like this doesn't apply to your situation.
This file is on a floppy, correct? See if you can copy the file from the floppy to your hard drive. If it won't copy you have developed some bad sectors on the floppy. Recover everything you can off of that disk and reformat it or throw it away! I learned my lesson the hard way a long time ago. Anything important that I save to a floppy I make sure I have at least one more floppy for a backup and also keep a copy on my hard drive.
If the file can be copied from the floppy, try opening it from your hard drive. If it won't open, it must have been corrupted in some other way. The only luck I've had is in using Excel on files that are corrupted, but that doesn't always work.
Wish I had better suggestions for you...