Thank you for your post.
First, I would update FileMaker Pro Advanced on your MacBook to version 8.5.2. Please see:
If another computer running 8.5 can also see the hosted files, then copy the server.pem file from the other machine to your MacBook. To get the server.pem file, right-click the FileMaker Pro Advanced 8.5 application, and select "Show Package Contents". Go to Contents -> Mac OS -> server.pem
Be sure to replace the existing server.pem file on your MacBook with the server.pem file from the working machine.
Let me know how this works out.
The solution was (it has been a while... pauses to confirm by looking at old emails) to reinstall Filemaker BUT ONLY AFTER setting the clock back to before Sept 22 2008! weird. but true. worked like a charm:
of course after the install set the clock back to today.