you mentioned a "fail" report. Is this a simple message or is this a "crash" report?
What is/are the InDesign version/s of the old files?
Do you have access to older versions of InDesign on your Mac? CS4, CS5, CS5.5 perhaps?
If yes, try to open the files there. But before: Do it with duplicates of the documents.
Speaking about "duplicates": How did you transfer the InDesign documents to your Mac?
Maybe the files went corrupt in the process of transfering them…
Most likely the files are damaged -- newer versions of ID should open legacy files without any problem.
Your crash report might provide a clue (but might not). Post it on pastebin.com, NOT HERE, and provide a link.
Yes, it's a crash report (used wrong name).
I unfortunately don't have older versions of ID on my Mac, I copied them from my old hard drive so as you say they might have been corrupted but that doesn't explain why I can open some and some not.