I have an Excel file on a floppy that was created in the year 2000 on a (now
deceased)
computer with WIN98 and Office 2000. I just tried to open it on my Panasonic
Toughbook with WIN98, also Office 2000. The Excel refuses to open it, saying
"file format is not valid". In spite of that, the Toughbook successfully
copied it from the floppy onto the hard disk using My Computer. I copied
that one onto another floppy and successfully opened it on my main computer
with Office 2000 and XP.

So how could the file format be a problem? The Excel on my Toughbook works
fine with other files. It even opens files created in Lotus 123 on a 286.
The only difference I can see with this one is it's
quite big (1.2M). I've been all over the Excel help and can't see anything
that seems to cover this.