Thank you for your post.
FileMaker Pro 5 is having difficulty opening the file. Try downloading the file to your local drive and see if you can open it. If it works, then you have a network issue. Obviously, this worked previously, so something has changed. You will need to do some sleuthing on your own.
Once you get FileMaker Pro 9 running, opening the FileMaker Pro 5 file will then convert to FileMaker 9 format. Once this is done, you can put it back on the network and try again.