Thanks for all your help guys. I found the culpirt. For some strange reason this particular formula was causing my problems.
=VLOOKUP(CONCATENATE(A6,$L$5),'[Division Raw Data.xls]Adjusted OH by Div'!$E:$F,2,FALSE)
I have a hidden row of formulas, and my macro uses this row to copy/paste to all rows below in my document, and then it copies/pastes the values of the cells (to reduce file space when saving). This one formula in my hidden row, when deleted, would allow the file to save normally when the macro runs. I then re-added this formula, and then I started getting my same problems. >=o( So.... I'm having my macro write the formula into the hidden row for me, , do its copy/pastes, and then delete it from the hidden row before saving the file.
I have no idea why this one formula would be causing all these problems. It's the only one I have with a concatenate, but still, I have other similar formulas in other documents... Sigh....
Thank you all so much for all of your help!