OK, so I now see what's going on.

the arrays in Col P don't like the columns they reference due to the
'blank but not really blank cells. For instance, Col O at O5379 is
=IF(ISNUMBER(K5379),SQRT(L5379^2+M5379^2+N5379^2), ""). It's that ""
that I used to return blank cells that messes it up. Anyone know of a
way to avoid using "" and still keep cells blank (hopefully w/o using
VBA since I never get it working right)?

Sorry to keep updating, but I keep thinking of ways to get at it after
I post.

Thanks again,
K