Working on excel2002 SP3

I got a workbook with a couple of links to another one - occasionally I want
them updated.
So, when I open it I choose "Update links" but then get a message "This
workbook contains one or more links that cannot be updated" with an option
"Edit links"
The next window shows me 2 links, the one that I know and another one (to
Mds97.xla) that I do not know. This one shows a status of "Error: Undefined
or non-rectangular reference"
How can I find where this reference is located so I can remove it?

Edit / Find (all) "[" does not show the mystery link.
There are no hidden sheets.
There are no macros.