There was a problem when using acrobat in an older version - could it be this issue here?
Apologies to Mary Pante. I thought I'd seen this one before, but a search of the Known Bugs List was coming up empty. With that hint from markus schneider, I was able to find it:
For More Information see: http://forums.filemaker.com/posts/1dd95f9381?page=1
This is one of many acknowledged bugs that can be found in the Known Bug List thread here in the Report an Issue section of the forum.
It can also be downloaded as a database file from: https://www.dropbox.com/s/jt09b82i0xijbu3/FMP%20Bugs.zip
Thanks to both markus schneider & PhilModJunk for the info!
I will try the solution mentioned in the provided thread as this seems to be the problem with my setup. I have Acrobat Pro 9 Extended installed on both computers so this must be the culprit.
Thanks again for being so helpful