#VALUE!

DennaB 

I can share in your blessing, but in my case three years ahead of you and still a few months away==I'll turn 80 in October.  I also share some of your experience as well--it wasn't my main career, but I did become something of a power user with Excel and its predecessors in the spreadsheet world (Lotus, Quattro), as well as learning SQL to write extensive queries from a mainframe database--and therefore can fully appreciate how frustrating it can be when, with all that experience, you can't put your finger on what's causing the #VALUE.

Unfortunately, an image isn't something that any of us can actually do much diagnostic work with.

Looking at the formula in the formula bar in the image, and the cell from which it appears to come (I748), I can tell:

• the formula IS working in I748
• and it's not in any of the subsequent rows--well, more precisely, it's working to deliver #VALUE

Which suggest something I'm sure you're well aware of, that the issue is most likely in whatever is in cells G749 and H749...and once introduced it doesn't self-correct since it's always in I749, I750, I751,... and on. Has the formula been changed in any way in any of the rows? I will offer the observation that the formula that's visible in this image is NOT the formula you included in your original post.

What happens if you place fresh numeric values in some of the cells in columns G, H and I down below where the #VALUE first appears? Down in the 760s?  

And since you made this image from a modified copy of the spreadsheet itself, is it now possible to post that actual--but modified and therefore not revealing sensitive personal data--spreadsheet?