Thanks for the useful help. Your suggestion number 2 works. I know
very well that .Columns needed to be qualified, I just wasn't seeing it
when reviewing my code.

Suggestion #1 doesn't work in my case. My program is a workbook
compare program. I have two directories that contains workbooks to be
compared, a "\before" directory and a "\after" directory. Suggestion
#1 would mean I'd have to instantiate Excel for every workbook I'm
processing.

Suggestion #3 isn't viable for my process because the workbook I have
open in the first instance of Excel has the same name as the workbook
in the second instance of Excel. Excel doesn't allow two workbooks of
the same name open at the same time even if they are in separate
directories.

My program compares each cell in the "before" workbook to each cell in
the "after" workbook and flags differences by cell.

Thanks again for your help!