Thanks Oldchippy,

I know how to find all my external links, what I'm trying to figure out is how internal links can spontaneously become external pointing to another file after 2 years.

Here's what the internal link looked like for 2 years

=+Input!N39+Input!AP39

Every month I'd update the file with new data and this reference would pick up the updated data just like it should.

Then after 2 years the formula suddenly changed to this

=+'T:\FY07\October\[oct final.xls]Input'!N39+'T:\FY07\October\[oct final.xls]Input'!AP39

Since I never go back and revise older month's, this October file would never get updated. So when I tried updating for November data, it was still picking up October's. It appeared to only happen in 1 tab, 1 column, but multiple cells just like this.

The rest of the file maintained all internal and external references as I put them in.

This scenario only happened to me once before. And now I find out, it's happened to others in my office and nobody knows what causes it.

It worries me because I can't be constantly checking to see if I have more external references than I intended.

Thanks again for your attention