I don't have a specific answer to your question. However, I would highly recommend upgrading to FileMaker Server 10, as there are a number of important bugs that were squashed since FileMaker Server 8.
Thank you for your post.
Mac OS X 10.5.6 is not supported for FileMaker Server 8. Knowledge Base article #6134 gives the system requirements for FileMaker Server 8. You can read it directly at:
I ended up updating to FM10 Server (which is what I wanted to do, but had to have a reason beyond new features as we're not using v10 client — still using v8.5 client, and that's not changing right now).