Thank you for your post.
Make sure you are running FileMaker Pro 8.5v2, as 8.5v2 is the first version certified to run on Leopard (Mac OS X 10.5.x). If you don't have 8.5v2, download it from our web site at:
If you already have FileMaker Pro 8.5v2, then something else is occurring on your system. Assuming FileMaker Pro 8.5 is installed correctly, create a new User account on your Mac, switch to the new user account and launch FileMaker Pro 8.5v2. Do you still get the error message? If not, then there is something in your original user account that is conflicting with FileMaker Pro. If you still get the error message, then either your copy of FileMaker Pro 8.5 is bad (download a new copy from the above link) or something in your system is conflicting with FileMaker Pro. Try reinstalling Mac OS X 10.5.8 on your computer and try again.
Thanks, this worked! Had some difficulty deleting some pesky files in the Library but finally it all worked. May thanks.