[Darryl Ramm]

What is a "guitar file"? You mean guitar audio you have tracked and is in the session?

What is the *exact* error message you are getting?

When Pro Tools says an audio file is missing it's likely just missing.

The most common cause of stuff like this is you not working carefully and not keeping audio assets (files) in the session folder. They are somewhere else on your PC and only moving the session folder to the Mac lost those files.

You can go back to the PC and do a "Save Copy In" that will move audio assets into the Copy you save. But you really should work out what you have been doing wrong and how to keep assets into the session folder.

You can also look around in Workplace>Session>Session Files and find where files are.

The Pro Tools Reference Guide has more details on all this.