Sounds like GB is looking for something that has become damaged.
Was the OS 10.3 installation disk that you used to replace the OS, an original or a Restore disk that you got from some other place?
When you had your crash, what was the problem? Was the HD replaced?
If the answer to that is NO, did you do a Format and Install or an Archive and Install?
What version of GB are you currently trying to launch?
Is there an Instrument Library folder in the /Library/Application Support/GarageBand folder?
What method and medium are you using to try to reinstall GB?
P
After a crash I replaced my operating software in my G4 Power Mac, which is currently running Panther 10.3.9. Garage Band no longer works. It's there but when I try to load it says "Instrument Linrary is invalid. Garageband expects a valid Instrument Library folder in
/Library/Application Support/GarageBand. Please choose a valid Instrument Library Folder or quit and re-install GarageBand."
The problem is I can'r reinstall it because when I try, this is the message that comes up again.
Any ideas?? Please....thank-you in advance!

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