Excel 2003 crashes on "save" or "save as"

[CHATTAX]

Today is 05/22/2018. I just noticed this problem yesterday. I am running Excel 2003 on a Lenovo machine running windows 10. I have a 2 page work book containing lists. Workbook is stored on a external hard drive attached to my machine. Not networked. No other access. No formulas. No macros. No links. The only formatting difference used is a single column in each worksheet that is formatted for "date" (MM/DD/YYYY). I was updating the workbook yesterday when excel simply crashed. No error message, no warning, it just crashed and all that was showing on my screen was my desktop. Re-open the workbook, and, of course, the changes have not been saved.

Checking the folder where the file is stored, I found that it had saved a new file to the folder. The new name was 7314D410). It was not an excel file, but opening it in either excel or word, what I could read of the data (most of it appeared to be machine-language) indicated that it's the first page of my original workbook.

I've tried "save as" renaming the workbook. Same result. I copied the data to a new spreadsheet. Same result. Interestingly, If I divide the workbook into two separate workbooks (one page each), it will save the changes and not crash.

I've run C-Cleaner to erase any temporary files I might have had. I've dumped the new files (7314D410, etc). I'm stuck. Anybody got any ideas?