Indiana University Music Library recently encountered and solved a problem with Finale 25/Aria Player, and I wanted to share our solution with you all just in case anyone else encounters this problem.
The problem was first noticed when Finale wouldn't play back all of it's sounds - SmartSynth worked fine but only a small number of the Garritan sounds were working. When trying to work with the Aria player, the error "slot 0" (or other numbers, depending) and "not found" would come up, with a long list of audio files it was missing. We tried many things, but in the end, here's what worked:
Finale 25 automatically installs the Aria samples to '/Users/Shared". For some reason (probably having to do with the school's software and policy of wiping certain files at the end of the night), this prevented Aria from finding the files, even though it was looking in the right place. These were the steps we took to resolve the issue:
1) Move the folder "GIFF_Samples" from "/Users/Shared" to "/Applications/Garritan Instruments for Finale"
2) Go to "/Library/Preferences" and locate the file "com.Garritan.Instruments for Finale.plist"
3) Replace the text "Users/Shared" with "Applications/Garritan Instruments for Finale". (Note, this plist is locked, so to do this we had to drag the file to the desktop which created an unlocked copy, delete the original file from Preferences, make the edits in the copied file, and move that edited file into the Preferences folder)
Do be careful - those other plist files can be crucial to the function of your computer, so don't mess with them.
Hope this is helpful, and perhaps prevents some headaches!